Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Mar. 31, 2018	May 21, 2018	Sep. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	EXP
Entity Registrant Name	EAGLE MATERIALS INC
Entity Central Index Key	0000918646
Current Fiscal Year End Date	--03-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		47,973,138
Entity Public Float			$ 5.1

Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenue	$ 1,386,520	$ 1,211,220	$ 1,143,492
Cost of Goods Sold	1,047,764	899,175	911,875
Gross Profit	338,756	312,045	231,617
Equity in Earnings of Unconsolidated Joint Venture	43,419	42,386	39,083
Corporate General and Administrative Expense	(41,205)	(33,940)	(37,193)
Legal Settlements	(45,098)
Other Non-Operating Income	3,728	2,139	2,328
Acquisition-Related Expense		(5,480)
Interest Expense, Net	(27,638)	(22,631)	(16,583)
Earnings before Income Taxes	271,962	294,519	219,252
Income Taxes	(15,330)	(96,300)	(66,660)
Net Earnings	$ 256,632	$ 198,219	$ 152,592
EARNINGS PER SHARE
Basic	$ 5.33	$ 4.14	$ 3.08
Diluted	$ 5.28	$ 4.10	$ 3.05
AVERAGE SHARES OUTSTANDING
Basic	48,141,226	47,931,518	49,471,157
Diluted	48,645,986	48,361,286	50,070,829
CASH DIVIDENDS PER SHARE	$ 0.40	$ 0.40	$ 0.40

Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net Earnings	$ 256,632	$ 198,219	$ 152,592
Net Actuarial Change in Defined Benefit Plans:
Unrealized gain (loss) during the period, net of tax (expense) benefit of ($1,995), ($1,544) and $488	3,407	2,765	(613)
Amortization of net actuarial loss, net of tax benefit of $301, $760 and $242	955	1,248	1,271
Reclassification of Income Tax Effects to Retained Earnings	(978)
Comprehensive Earnings	$ 260,016	$ 202,232	$ 153,250

Consolidated Statements of Comprehensive Earnings (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Unrealized gain (loss) during the period, tax (expense) benefit	$ (1,995)	$ (1,544)	$ 488
Amortization of Net Actuarial Loss, tax benefit	$ 301	$ 760	$ 242

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Current Assets -
Cash and Cash Equivalents	$ 9,315	$ 6,561
Restricted Cash	38,753
Accounts and Notes Receivable, net	141,685	136,313
Inventories	258,159	252,846
Income Tax Receivable	5,750
Prepaid and Other Assets	5,073	4,904
Total Current Assets	458,735	400,624
Property, Plant, and Equipment -	2,586,528	2,439,438
Less: Accumulated Depreciation	(991,229)	(892,601)
Property, Plant, and Equipment, net	1,595,299	1,546,837
Notes Receivable	115	815
Investment in Joint Venture	60,558	48,620
Goodwill and Intangible Assets, net	239,342	235,505
Other Assets	13,954	14,723
Total Assets	2,368,003	2,247,124
Current Liabilities -
Accounts Payable	73,459	92,193
Accrued Liabilities	105,870	55,379
Income Tax Payable		733
Current Portion of Long-term Debt		81,214
Total Current Liabilities	179,329	229,519
Long-term Debt	620,922	605,253
Other Long-term Liabilities	31,096	42,878
Deferred Income Taxes	118,966	166,024
Total Liabilities	950,313	1,043,674
Stockholders’ Equity –
Preferred Stock, Par Value $0.01; Authorized 5,000,000 Shares; None Issued
Common Stock, Par Value $0.01; Authorized 100,000,000 Shares; Issued and Outstanding 48,282,784 and 48,453,268 Shares, respectively.	483	485
Capital in Excess of Par Value	122,379	149,014
Accumulated Other Comprehensive Losses	(4,012)	(7,396)
Retained Earnings	1,298,840	1,061,347
Total Stockholders’ Equity	1,417,690	1,203,450
Liabilities and Stockholders' Equity, Total	$ 2,368,003	$ 2,247,124

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Mar. 31, 2017
Statement Of Financial Position [Abstract]
Preferred Stock, Par Value	$ 0.01	$ 0.01
Preferred Stock, Authorized	5,000,000	5,000,000
Preferred Stock, Issued	0	0
Common Stock, Par Value	$ 0.01	$ 0.01
Common Stock, Authorized	100,000,000	100,000,000
Common Stock, Issued	48,282,784	48,453,268
Common Stock, Outstanding	48,282,784	48,453,268

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net Earnings	$ 256,632	$ 198,219	$ 152,592
Adjustments to Reconcile Net Earnings to Net Cash Provided by Operating Activities, Net of Effect of Non-Cash Activity -
Depreciation, Depletion and Amortization	114,015	91,791	97,105
Inventory Adjustment to Net Realizable Value		8,492	9,382
Impairment of Intangible Assets			34,999
Reduction of Prepaid Sand Liability		(2,000)	(10,658)
Deferred Income Tax Provision	(49,354)	2,203	(2,323)
Stock Compensation Expense	14,079	12,069	17,346
Excess Tax Benefits from Share-Based Payment Arrangements		(10,349)	(4,102)
Equity in Earnings of Unconsolidated Joint Venture	(43,419)	(42,386)	(39,083)
Distributions from Joint Venture	31,500	43,250	37,250
Changes in Operating Assets and Liabilities:
Accounts and Notes Receivable	(2,560)	(14,235)	(4,553)
Inventories	(5,114)	(6,636)	(15,122)
Accounts Payable and Accrued Liabilities	24,173	33,687	(7,061)
Other Assets	4,196	788	4,468
Income Taxes Payable (Receivable)	(6,483)	16,705	(4,473)
Net Cash Provided by Operating Activities	337,665	331,598	265,767
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment	(131,957)	(56,938)	(89,563)
Acquisition Spending	(36,761)	(400,488)	(32,427)
Net Cash Used in Investing Activities	(168,718)	(457,426)	(121,990)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase (Decrease) in Credit Facility	15,000	(157,000)	52,000
Repayment of Senior Notes	(81,214)	(8,000)	(57,045)
Issuance of Long-term Debt		350,000
Dividends Paid to Stockholders	(19,438)	(19,341)	(20,020)
Purchase and Retirement of Common Stock	(61,078)	(60,013)	(123,530)
Proceeds from Stock Option Exercises	24,264	22,108	2,866
Shares Redeemed to Settle Employee Taxes on Stock Compensation	(4,974)	(4,468)	(4,273)
Payment of Debt Issuance Costs		(6,637)
Excess Tax Benefits from Share-Based Payment Arrangements		10,349	4,102
Net Cash Provided by (Used in) Financing Activities	(127,440)	126,998	(145,900)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	41,507	1,170	(2,123)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD	6,561	5,391	7,514
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	$ 48,068	$ 6,561	$ 5,391

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Losses [Member]
Beginning balance at Mar. 31, 2015	$ 1,010,593	$ 502	$ 272,441	$ 749,717	$ (12,067)
Net Earnings	152,592			152,592
Stock Option Exercises and Restricted Share Vesting	2,866	2	2,864
Tax Benefit-Stock Option Exercise	4,102		4,102
Purchase and Retirement of Common Stock	(123,530)	(19)	(123,511)
Dividends to Stockholders	(19,823)			(19,823)
Stock Compensation Expense	17,346		17,346
Shares Redeemed to Settle Employee Taxes	(4,273)		(4,273)
Unfunded Pension Liability, net of tax	658				658
Ending Balance at Mar. 31, 2016	1,040,531	485	168,969	882,486	(11,409)
Net Earnings	198,219			198,219
Stock Option Exercises and Restricted Share Vesting	22,108	8	22,100
Tax Benefit-Stock Option Exercise	10,349		10,349
Purchase and Retirement of Common Stock	(60,013)	(9)	(60,004)
Dividends to Stockholders	(19,358)			(19,358)
Stock Compensation Expense	12,069	1	12,068
Shares Redeemed to Settle Employee Taxes	(4,468)		(4,468)
Unfunded Pension Liability, net of tax	4,013				4,013
Ending Balance at Mar. 31, 2017	1,203,450	485	149,014	1,061,347	(7,396)
Net Earnings	256,632			256,632
Stock Option Exercises and Restricted Share Vesting	24,264	3	24,261
Purchase and Retirement of Common Stock	(61,078)	(5)	(61,073)
Dividends to Stockholders	(19,404)			(19,404)
Stock Compensation Expense	14,079		14,079
Cumulative Impact of the Adoption of ASU 2016-09			713	(713)
Reclassification of Income Tax Effects to Retained Earnings				978	(978)
Shares Redeemed to Settle Employee Taxes	(4,974)		(4,974)
Other	359		359
Unfunded Pension Liability, net of tax	4,362				4,362
Ending Balance at Mar. 31, 2018	$ 1,417,690	$ 483	$ 122,379	$ 1,298,840	$ (4,012)

SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

(A) Significant Accounting Policies

Basis of Presentation

The consolidated financial statements include the accounts of Eagle Materials Inc. and its majority-owned subsidiaries (the Company), which may be referred to as we, our, or us. All intercompany balances and transactions have been eliminated. The Company is a holding company whose assets consist of its investments in its subsidiaries, joint venture, intercompany balances and holdings of cash and cash equivalents. The businesses of the consolidated group are conducted through the Company’s subsidiaries. The Company conducts one of its cement plant operations through a joint venture, Texas Lehigh Cement Company L.P., which is located in Buda, Texas (the Joint Venture). Our investment in the Joint Venture is accounted for using the equity method of accounting, and those results have been included for the same period as our March 31 fiscal year end.

The preparation of financial statements in conformity with accounting principles generally accepted in the U.S. requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.

Cash and Cash Equivalents

Cash equivalents include short-term, highly liquid investments with original maturities of three months or less and are recorded at cost, which approximates market value.

Restricted Cash

Restricted cash includes amounts deposited in a qualified settlement fund. These amounts were deposited in relation to our settlement of a class action lawsuit. Upon final approval of the District Court, these funds will be transferred to the plaintiff’s attorneys. See Footnote (I) Commitments and Contingencies for more information regarding the lawsuit and settlement.

Accounts and Notes Receivable

Accounts and notes receivable have been shown net of the allowance for doubtful accounts of
$8.6 million and $10.7 million at March 31, 2018 and 2017, respectively. During fiscal 2018, we charged approximately $0.8 million to bad debt expense and wrote-off approximately $2.9 million of uncollectible accounts. We perform ongoing credit evaluations of our customers’ financial condition and generally require no collateral from our customers. The allowance for non-collection of receivables is based upon analysis of economic trends in the construction and oil and gas industries, detailed analysis of the expected collectability of accounts receivable that are past due, and the expected collectability of overall receivables. We have no significant credit risk concentration among our diversified customer base.

We had notes receivable totaling approximately $2.3 million at March 31, 2018, of which approximately $2.2 million has been classified as current and presented with accounts receivable on the balance sheet. We lend funds to certain companies in the ordinary course of business, and the notes bear interest, on average, at LIBOR plus 3.5%, which was approximately 5.1% on March 31, 2018. Remaining unpaid amounts, plus accrued interest, mature in fiscal 2019 and 2021. The notes are collateralized by certain assets of the borrowers, namely property and equipment. We monitor the credit risk of each borrower by focusing on the timeliness of payments, review of credit history, and credit metrics and interaction with the borrowers.

Inventories

Inventories are stated at the lower of average cost (including applicable material, labor, depreciation, and plant overhead) or market. Inventories consist of the following:

	March 31,
	2018		2017
	(dollars in thousands)
Raw Materials and Materials-in-Progress	$	121,628	$	122,736
Finished Cement		24,089		24,428
Aggregates		7,787		7,686
Gypsum Wallboard		8,477		7,951
Paperboard		8,602		8,635
Frac Sand		1,696		2,907
Repair Parts and Supplies		79,878		73,732
Fuel and Coal		6,002		4,771
	$	258,159	$	252,846

During fiscal 2017, we wrote down approximately $7.7 million of raw materials and $0.8 million of materials-in-process and frac sand. These inventories are tied to our Oil and Gas Proppants sector.

Property, Plant, and Equipment

Property, plant, and equipment are stated at cost. Major renewals and improvements are capitalized and depreciated. Annual maintenance is expensed as incurred. Depreciation is provided on a straight-line basis over the estimated useful lives of depreciable assets and totaled $109.6 million, $86.0 million, and $84.2 million for the years ended March 31, 2018, 2017, and 2016, respectively. Raw material deposits are depleted as such deposits are extracted for production utilizing the units-of-production method. Costs and accumulated depreciation applicable to assets retired or sold are eliminated from the accounts and any resulting gains or losses are recognized at such time. The estimated lives of the related assets are as follows:


Plants		20 to 30 years
Buildings		20 to 40 years
Machinery and Equipment		3 to 25 years

We periodically evaluate whether current events or circumstances indicate that the carrying value of our depreciable assets may not be recoverable. At March 31, 2018 and 2017, management believes no events or circumstances indicate that the carrying value may not be recoverable.

Impairment or Disposal of Long-Lived and Intangible Assets

We evaluate the recoverability of our long-lived assets and certain identifiable intangibles, such as permits and customer contracts, for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets, such as plants, buildings, and machinery and equipment, including mining assets, is measured by comparing the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset. Such evaluations for impairment are significantly affected by estimates of future prices for our products, capital needs, economic trends in the construction sector and other factors. If such assets are considered to be impaired, we determine the dollar amount of the impairment to be recognized by subtracting the estimated fair value of the assets from their carrying value. The amount by which the carrying value of the assets exceeds their estimated fair value is the impairment amount we recognize. Assets to be disposed of by sale are reflected at the lower of their carrying amount or fair value less cost to sell.

During calendar 2015, the continued decline in oil prices adversely affected oil and gas drilling activity, leading to further reductions in demand and pricing for proppants. This reduction in demand adversely affected performance under our customer contracts for our frac sand business, resulting in the amendment of certain of these contracts. Based on the reduced demand for proppants and the executed and pending amendments to our customer contracts, we concluded that long‒lived asset impairment indicators were present during the quarters ended September 30, 2015 and March 31, 2016 for our customer contract intangible assets. We performed recovery tests to determine if any of the customer contract intangible assets related to our Oil and Gas Proppants business unit were impaired at September 30, 2015, and March 31, 2016. Based on our analysis of the undiscounted cash flows for each of our customer contract intangibles related to our Oil and Gas Proppants business, we concluded that the carrying value of certain customer contract intangible assets exceeded the undiscounted cash flows for the related assets at both September 30, 2015 and March 31, 2016. For those contracts whose carrying value exceeded the undiscounted cash flows, we calculated an estimated fair value of each contract using the weighted-average probable cash flows related to each contract (level 3 inputs), discounted using a weighted-average cost of capital (WACC). The WACC was determined from relevant market comparisons and adjusted for specific risks. This analysis resulted in impairment losses of approximately $28.4 million and $6.6 million for the quarters ended September 30, 2015, and March 31, 2016, respectively, which is included in Cost of Goods Sold in the Consolidated Statement of Earnings for fiscal year 2016. There was no impairment of long-lived and intangible assets during fiscal 2018 and 2017.

Goodwill and Intangible Assets

Goodwill

Goodwill is subject to at least an annual assessment for impairment by applying a fair value–based test. We have elected to test for goodwill impairment in the fourth quarter of each fiscal year. The goodwill impairment test is a two-step process that requires us to make judgments in determining which assumptions to use in the calculation. The first step consists of estimating the fair value of each reporting unit based on a discounted cash flow model using revenue and profit forecasts and comparing those estimated fair values with the carrying value. The second step is performed, if necessary, to compute the amount of the impairment by determining an implied fair value of goodwill. Similar to the review for impairment of other long-lived assets, evaluations for impairment are significantly affected by estimates of future prices for our products, capital needs, economic trends, and other factors.

Intangible Assets

Intangible Assets, including the impact of the impairment charges discussed above, at March 31, 2018 and 2017, consist of the following:

	March 31, 2018
	Amortization Period	Cost		Accumulated Amortization			Net
	(dollars in thousands)
Goodwill and Intangible Assets:
Customer Contracts and Relationships	15 years	$	72,260	$	(58,732	)	$	13,528
Sales Contracts	4 years		2,500		(2,500	)		—
Permits	40 years		28,640		(8,037	)		20,603
Goodwill			205,211		—			205,211
Total Goodwill and Intangible Assets		$	308,611	$	(69,269	)	$	239,342

	March 31, 2017
	Amortization Period	Cost		Accumulated Amortization			Net
	(dollars in thousands)
Goodwill and Intangible Assets:
Customer Contracts and Relationships	15 years	$	72,260	$	(56,303	)	$	15,957
Sales Contracts	4 years		2,500		(2,500	)	$	—
Permits	40 years		28,440		(7,262	)	$	21,178
Goodwill			198,370		—		$	198,370
Total Goodwill and Intangible Assets		$	301,570	$	(66,065	)	$	235,505

At March 31, 2018, approximately $1.6 million of customer contracts and relationships were related to our Oil and Gas Proppants sector.

During fiscal 2017, we wrote off a customer contract in our Oil and Gas Proppants segment valued at $1.3 million due to the termination of the contract. At March 31, 2016, we had a $2.0 million liability related to prepayment for sand under one of our contracts. This contract expired on June 30, 2016, at which time the customer prepayment was forfeited under the terms of the contract. The $2.0 million was recorded as a reduction of Cost of Goods Sold in our fiscal 2017 Consolidated Statement of Earnings.

During fiscal 2017, sales contracts with two of our customers in our Oil and Gas Proppants segment expired or were terminated. These customers had not purchased their contractually required amounts at the time the contracts expired or were terminated, and we entered into settlement agreements with those customers in connection with their failure to purchase the contractually required amounts. Based on these agreements, we received settlement payments of approximately $12.9 million in exchange for releasing our claims against such customers. The settlement payments were recorded as a reduction of Cost of Goods Sold in our fiscal 2017 Consolidated Statement of Earnings.

Amortization expense of intangibles was $4.4 million, $4.8 million, and $12.9 million for the years ended March 31, 2018, 2017, and 2016, respectively. Amortization expense is expected to be approximately $3.2 million for fiscal year 2019, $2.2 million for fiscal year 2020, and $1.7 million for fiscal years 2021, 2022, and 2023.

Other Assets

Other Assets are primarily composed of financing costs related to our revolving credit facility, deferred expenses, and deposits.

Income Taxes

Income Taxes are accounted for using the asset and liability method. The effect on deferred taxes of a change in tax rates is recognized in earnings in the period that includes the enactment date. Deferred taxes are recognized for the differences between financial statement carrying amounts and the tax bases of existing assets and liabilities by applying enacted statutory tax rates for future years. In addition, we recognize future tax benefits to the extent that such benefits are more likely than not to be realized.

Stock Repurchases

On August 10, 2015, the Board of Directors authorized the Company to repurchase up to an additional 6,782,700 shares, for a total outstanding authorization of 7,500,000 shares. During fiscal 2018, 2017, and 2016, we repurchased 627,772; 788,800; and 1,894,000 shares, respectively, at average prices of $97.30, $76.08, and $65.24, respectively. Subsequent to March 31, 2018, we repurchased an additional 319,300 shares through May 21, 2018, at an average price per share of $101.39. Including the share repurchases made subsequent to March 31, 2018, we have authorization to repurchase an additional 3,870,128 shares.

Revenue Recognition

Revenue from the sale of cement, concrete and aggregates, gypsum wallboard, recycled paperboard, and oil and gas proppants is recognized when title and ownership are transferred upon shipment to the customer. Freight and delivery charges paid by us for the delivery of goods to our customers is billed to the customer. Fees for shipping and handling that are billed to the customer are recorded as revenue, while costs incurred for shipping and handling are recorded as expenses and included in cost of goods sold. Revenue from transload services and storage is recognized when the product is transferred from the rail car to the truck or silo, or from the silo to the railcar or truck.

Approximately $158.3 million, $138.0 million, and $139.5 million of freight for the years ended March 31, 2018, 2017 and 2016, respectively, were included in both revenue and cost of goods sold in our Consolidated Statement of Earnings.

Other non-operating revenue (loss) includes lease and rental income, asset sale income, non-inventoried aggregates sales income, distribution center income, and trucking income, as well as other miscellaneous revenue items and costs which have not been allocated to a business segment.

Comprehensive Income/Losses

As of March 31, 2018, we have an accumulated other comprehensive loss of $4.0 million, which is net of income taxes of $1.3 million, in connection with recognizing the difference between the fair value of the pension assets and the projected benefit obligation.

Consolidated Cash Flows – Supplemental Disclosures

Interest payments made during the years ended March 31, 2018, 2017, and 2016 were $28.9 million, $19.0 million, and $16.9 million, respectively.

We made net payments of $69.4 million, $76.1 million, and $63.9 million for federal and state income taxes in the years ended March 31, 2018, 2017, and 2016, respectively.

Statements of Consolidated Earnings – Supplemental Disclosures

Maintenance and repair expenses are included in each segment’s costs and expenses. We incurred $107.3 million, $101.5 million, and $95.1 million in the years ended March 31, 2018, 2017, and 2016, respectively, which is included in Cost of Goods Sold on the Consolidated Statement of Earnings.

Selling, General and Administrative Expenses

Selling, General, and Administrative expenses of the operating units are included in Cost of Goods Sold on the Consolidated Statements of Earnings. Corporate General and Administrative (Corporate G&A) expenses include administration, financial, legal, employee benefits, and other corporate activities, and are shown separately in the Consolidated Statements of Earnings. Corporate G&A also includes stock compensation expense. See Note (J), Stock Option Plans, for more information.

Total Selling, General, and Administrative expenses for each of the periods are summarized as follows:

	For the Years Ended March 31,
	2018		2017		2016
	(dollars in thousands)
Operating Units Selling, G&A	$	62,529	$	57,004	$	56,110
Corporate G&A		41,205		33,940		37,193
	$	103,734	$	90,944	$	93,303

Earnings Per Share

	For the Years Ended March 31,
	2018			2017			2016
Weighted-Average Shares of Common Stock Outstanding		48,141,226			47,931,518			49,471,157
Effect of Dilutive Shares:
Assumed Exercise of Outstanding Dilutive Options		1,013,764			1,000,556			1,146,807
Less Shares Repurchased from Proceeds of Assumed Exercised Options		(727,904	)		(726,223	)		(768,886	)
Restricted Stock Units		218,900			155,435			221,751
Weighted-Average Common Stock and Dilutive Securities Outstanding		48,645,986			48,361,286			50,070,829

The line Less Shares Repurchased from Proceeds of Assumed Exercised Options includes unearned compensation related to outstanding stock options.

There were 98,362; 513,262; and 688,420 stock options at an average exercise price of $98.75 per share, $80.59 per share, and $80.51 per share, respectively, that were excluded from the computation of diluted earnings per share for the years ended March 31, 2018, 2017, and 2016, respectively, because such inclusion would have been anti-dilutive.

Share-Based Compensation

All share-based compensation is valued at the grant date and expensed over the requisite service period, which is generally identical to the vesting period of the award. Forfeitures of share-based awards are recognized in the period in which they occur.

Fair Value Measures

Certain assets and liabilities are required to be recorded or disclosed at fair value. The estimated fair values of those assets and liabilities have been determined using market information and valuation methodologies. Changes in assumptions or estimation methods could affect the fair value estimates; however, we do not believe any such changes would have a material impact on our financial condition, results of operations, or cash flows. There are three levels of inputs that may be used to measure fair value:

Level 1 – Quoted prices for identical assets and liabilities in active markets;

Level 2 – Quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data; and

Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs.

Recent Accounting Pronouncements

RECENTLY ADOPTED

In March 2016, the Financial Accounting Standards Board (FASB), issued Accounting Standards Update (ASU) 2016-09, “Improvements to Employee Share-Based Payment Accounting,” which provides for simplification of certain aspects of employee share-based payment accounting, including income taxes, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The Company adopted ASU 2016-09 on April 1, 2017. The new standard provides for changes to accounting for stock compensation, including 1) Excess tax benefits and tax deficiencies related to share-based payment awards will be recognized as income tax benefit or expense in the reporting period during which they occur; 2) Excess tax benefits will be classified as an operating activity in the statement of cash flow; 3) The option to elect estimating forfeitures or accounting for them when they occur; and 4) An increase in the tax withholding requirements threshold to qualify for equity classification. The primary impact of adoption was the recognition of excess tax benefits for our stock awards in the provision for income taxes rather than additional paid-in capital. As provided by the new standard, the Company changed its method of accounting for forfeitures, and will now recognize forfeitures as they occur. This resulted in a reduction of approximately $0.7 million to retained earnings. Additional amendments to the accounting for income taxes and minimum statutory withholding tax requirements had no impact to retained earnings.

Adoption of the new standard resulted in the recognition of excess tax benefits in our provision for income taxes rather than paid-in capital of $4.1 million for fiscal 2018. The presentation of excess tax benefits on stock-based compensation was adopted prospectively within the Consolidated Statements of Cash Flows. The presentation requirements for cash flows related to employee taxes paid for withheld shares had no impact on any of the periods presented on the unaudited Condensed Consolidated Statements of Cash Flows as the Company has historically presented them as a financing activity.

In November 2016, the FASB issued ASU 2016-18 “Statement of Cash Flows,” which provides additional guidance on the presentation of restricted cash in the statement of cash flows. Under ASU 2016-18, restricted cash should be included with cash and cash equivalents on the statement of cash flows, instead of being classified as a component of operating or investing cash flows. The Company early adopted this standard on January 1, 2018. There is no impact to previous fiscal years related to the adoption of this standard.

In February 2018, the FASB issued ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” which allows the reclassification from accumulated other comprehensive income to retained earnings stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017. The ASU also requires companies to disclose their accounting policy for releasing income tax effects from accumulated other comprehensive income. The Company prospectively adopted this standard on March 31, 2018. As a result of the adoption, we reclassified approximately $1.0 million of income tax effect related to the Tax Cuts and Jobs Act from accumulated other comprehensive loss to retained earnings on March 31, 2018.

PENDING ADOPTION

In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers.” ASU 2014-09 supersedes the revenue recognition requirements in “Revenue Recognition (Topic 605),” and requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. The standard will be effective for us in the first quarter of fiscal 2019. We will adopt the new standard using the modified retrospective approach, which requires the standard be applied only to the most current period presented, with the cumulative effect of initially applying the standard recognized at the date of initial application. We performed an evaluation of all segments and do not expect the adoption of this standard to materially affect our consolidated financial statements.

In March 2017, the FASB issued ASU 2017-07, “Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” which revises the accounting for periodic pension and postretirement expense. This ASU requires net periodic benefit cost, with the exception of service cost, to be presented retrospectively as nonoperating expense. Service cost will remain a component of cost of goods sold and represent the only cost of pension and postretirement expense eligible for capitalization. We will adopt the standard on April 1, 2018 using the retrospective method for presentation of service cost and other components in the income statement. We will prospectively adopt the requirement to limit the capitalization of benefit cost to the service cost component. The impact of adopting this standard will be a reduction to cost of goods sold and an increase in other expense. Had we adopted this standard on April 1, 2017, our gross profit for fiscal 2018 would have increased by approximately $0.8 million, and other income would have decreased by $0.8 million.

In January 2017, the FASB issued ASU 2017-04 “Simplifying the Test for Goodwill Impairment,” which eliminates the second step of the goodwill impairment test. Under the new standard, an entity should recognize an impairment charge for the amount by which the carrying value of the reporting unit exceeds the reporting unit’s fair value. This standard is effective for us in the first quarter of fiscal 2021. We will early adopt this standard effective April 1, 2018, and it will be effective for annual goodwill impairment tests in the fourth quarter of fiscal 2019.

In February 2016, the FASB issued ASU 2016-02, “Leases,” which supersedes existing lease guidance to require lessees to recognize assets and liabilities on the balance sheet for the rights and obligations created by long-term leases and to disclose additional quantitative and qualitative information about leasing arrangements. The standard will be effective for us in the first quarter of fiscal 2020, and we will adopt using the modified retrospective approach. We are currently assessing the impact of the ASU on our consolidated financial statements and disclosures, as well as our internal lease accounting processes.

In January 2018, the FASB issued ASU 2018-01, “Land Easement Practical Expedient for Transition to Topic 842.” This ASU permits the election not to evaluate land easements under the new lease guidance that existed or expired before the adoption of the ASU 2016-02 and that were not previously accounted for as leases. We will adopt ASU 2018-01 concurrently with the adoption of ASU 2016-02.

Acquisition-Related Expense

Acquisition-related expense consists primarily of expenses incurred during the Fairborn Acquisition, as discussed in Footnote (B) to the Consolidated Financial Statements.

ACQUISITIONS

12 Months Ended

Mar. 31, 2018

Business Combinations [Abstract]

ACQUISITIONS

(B) ACQUISITIONS

Fairborn Acquisition

On February 10, 2017, we completed the previously announced acquisition (the Fairborn Acquisition) of certain assets of Cemex Construction Materials Atlantic, LLC (the Seller). The assets acquired by the Company in the Fairborn Acquisition include a cement plant located in Fairborn, Ohio, a cement distribution terminal located in Columbus, Ohio, and certain other related assets.

Purchase Price

The purchase price (the Fairborn Purchase Price) of the Fairborn Acquisition was approximately $400.5 million. We funded the payment of the Fairborn Purchase Price at closing and expenses incurred in connection with the Fairborn Acquisition through a combination of cash on hand and borrowings under our bank credit facility.

Recording of assets acquired and liabilities assumed

The transaction has been accounted for using the acquisition method of accounting. This requires, among other things, that assets acquired and liabilities assumed are recognized at their fair values as of the acquisition date. The Company engaged a third party to perform appraisal valuation to support the Company’s preliminary estimate of the fair value of certain assets acquired in the Fairborn Acquisition.

During the quarter ended December 31, 2017, we completed our mine plan enabling us to finalize the asset retirement obligation at the date of purchase. Based on the updated mine plan, the asset retirement obligation and corresponding asset was revised to approximately $2.8 million from $4.0 million.

The preparation of the valuation of the assets acquired and liabilities assumed in the Fairborn Acquisition requires the use of significant assumptions and estimates. Critical estimates include, but are not limited to, replacement value and condition of property and equipment, future expected cash flows, including projected revenue and expenses, and applicable discount rates for intangible and other assets. These estimates are based on assumptions that we believe to be reasonable. However, actual results may differ from these estimates.

The following table summarizes the allocation of the Fairborn Purchase Price to assets acquired and liabilities assumed as of the acquisition date:

Purchase Price Allocation at Acquisition Date

	As of February 10, 2017
	(dollars in thousands)
Inventories	$	11,106
Property and Equipment		314,897
Intangible Assets		10,000
Other Assets		2,820
Asset Retirement Obligation		(2,820	)
Total Net Assets		336,003
Goodwill		64,485
Total Estimated Purchase Price	$	400,488

Goodwill represents the excess purchase price over the fair values of assets acquired and liabilities assumed. The goodwill was generated by the availability of co-product sales and the opportunity associated with the expansion of our cement business to the eastern region of the United States. All the goodwill generated by the transaction will be deductible for income tax purposes.

Intangible Assets

The following table is a summary of the fair value estimates of the identifiable intangible assets (dollars in thousands) and their weighted-average useful lives:

	Weighted Average Life		Estimated Fair Value
Customer Relationships		15		9,000
Permits		40		1,000
Total Intangible Assets			$	10,000

Actual and pro forma impact of the Fairborn Acquisition

The following table presents the net sales and operating loss related to the Fairborn Acquisition that has been included in our Consolidated Statement of Earnings from February 10, 2017 through the end of the fiscal year:

	For the Fiscal Year Ended March 31,
	2017
	(dollars in thousands)
Revenue	$	7,022
Operating Income (Loss)	$	(2,394	)

Operating Income shown above for fiscal 2018 has been affected by approximately $14.6 million and $0.5 million related to depreciation and amortization, and the recording of acquired inventory at fair value, respectively. Operating Loss shown above for fiscal 2017 was affected by approximately $1.9 million and $1.5 million related to depreciation and amortization, and the recording of acquired inventory at fair value, respectively.

The unaudited pro forma results presented below include the effects of the Fairborn Acquisition as if it had been consummated as of April 1, 2015. The pro forma results include the amortization associated with an estimate for acquired intangible assets, interest expense associated with debt used to fund the Fairborn Acquisition, and depreciation from the fair value adjustments for property and equipment. To better reflect the combined operating results, approximately $5.5 million of material nonrecurring charges have been excluded from pro forma net income for fiscal 2016.

	For the Fiscal Year Ended March 31,
	2017		2016
	(dollars in thousands)
Revenue	$	1,280,511	$	1,218,254
Net Income	$	205,343	$	156,465
Earnings per share – basis	$	4.28	$	3.16
Earnings per share - diluted	$	4.25	$	3.12

The pro forma results do not include any anticipated synergies or other expected benefits of the Fairborn Acquisition. Accordingly, the unaudited pro forma results are not necessarily indicative of either future results of operations or results that might have been achieved had the Fairborn Acquisition been consummated as of April 1, 2015.

Wildcat Acquisition

On July 27, 2017, we acquired all of the outstanding equity interests in Wildcat Minerals LLC (the Wildcat Acquisition). Wildcat Minerals LLC operates transload facilities serving the oil and gas industry in several oil and gas basins across the United States. The purchase price (the Purchase Price) of the Wildcat Acquisition was approximately $36.8 million, subject to adjustments for working capital and other customary post-closing adjustments. The Purchase Price was allocated as follows: approximately $3.1 million to current assets, $28.3 million to property and equipment, $1.4 million to intangible and other assets, $2.8 million to current liabilities and $6.8 million to goodwill. The Purchase Price and expenses incurred in connection with the Wildcat Acquisition were funded through operating cash flow and borrowings under our bank credit facility. Assets related to the Wildcat Acquisition will be included in the Corporate and Other segment in our segment reporting.

PROPERTY, PLANT AND EQUIPMENT

12 Months Ended

Mar. 31, 2018

Property Plant And Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT

Cost by major category and accumulated depreciation are summarized as follows:

	March 31,
	2018			2017
	(dollars in thousands)
Land and Quarries	$	423,543		$	402,698
Plants		1,871,213			1,820,908
Buildings, Machinery and Equipment		187,484			175,526
Construction in Progress		104,288			40,306
		2,586,528			2,439,438
Accumulated Depreciation		(991,229	)		(892,601	)
	$	1,595,299		$	1,546,837

ACCRUED EXPENSES

12 Months Ended

Mar. 31, 2018

Payables And Accruals [Abstract]

ACCRUED EXPENSES

(D) Accrued Expenses

Accrued expenses consist of the following:

	As of March 31,
	2018		2017
	(dollars in thousands)
Payroll and Incentive Compensation	$	25,290	$	22,850
Benefits		13,785		11,503
Interest		3,852		5,992
Property Taxes		5,422		4,759
Power and Fuel		1,545		1,536
Litigation Settlements		45,098		—
Legal		1,435		2,459
Sales and Use Tax		890		944
Acquisition Related Expenses		—		350
Other		8,553		4,986
	$	105,870	$	55,379

INDEBTEDNESS

12 Months Ended

Mar. 31, 2018

Debt Disclosure [Abstract]

INDEBTEDNESS

(E) Indebtedness

Long-term debt consists of the following:

	As of March 31,
	2018			2017
	(dollars in thousands)
Bank Credit Facility	$	240,000		$	225,000
4.500% Senior Unsecured Notes Due 2026		350,000			350,000
Private Placement Senior Unsecured Notes		36,500			117,714
Total Debt		626,500			692,714
Less: Current Portion of Long-term Debt		—			(81,214	)
Less: Debt Origination Costs		(5,578	)		(6,247	)
Long-term Debt	$	620,922		$	605,253

The weighted-average interest rate of our Private Placement Senior Unsecured Notes was 6.0%, 6.0%, and 5.9% during fiscal 2018, 2017, and 2016, respectively, while the average interest rate at March 31, 2018 and 2017 was 6.5% and 6.0%, respectively.

The weighted-average interest rate of borrowings under our Credit Facility during fiscal 2018, 2017, and 2016 was 2.6%, 1.9%, and 1.6%, respectively. The interest rate on the Credit Facility was 3.2% and 2.4% at March 31, 2018 and 2017, respectively.

Our maturities of long-term debt during the next five fiscal years and thereafter are as follows:

Fiscal Year	Amount
2019	$	—
2020		36,500
2021		—
2022		240,000
2023		—
Thereafter		350,000
Total	$	626,500

Credit Facility

We have a $500.0 million revolving credit facility (the Credit Facility), including a swingline loan sublimit of $25.0 million, which terminates on August 2, 2021. Borrowings under the Credit Facility are guaranteed by substantially all of the Company’s subsidiaries. The debt under the Credit Facility is not rated by ratings agencies.

At our option, outstanding principal amounts on the Credit Facility bear interest at a variable rate equal to (i) LIBOR, plus an agreed margin (ranging from 100 to 225 basis points), which is to be established quarterly based upon the Company’s ratio of consolidated EBITDA, defined as earnings before interest, taxes, depreciation and amortization, to the Company’s consolidated indebtedness (the Leverage Ratio), or (ii) an alternative base rate which is the higher of (a) the prime rate or (b) the federal funds rate plus ¹/₂% per annum plus an agreed margin (ranging from 0 to 125 basis points). Interest payments are payable, in the case of loans bearing interest at a rate based on the federal funds rate, quarterly, or in the case of loans bearing interest at a rate based on LIBOR, at the end of the LIBOR advance periods, which can be a period of up to nine months at the option of the Company. The Company is also required to pay a commitment fee on unused available borrowings under the Credit Facility ranging from 10 to 35 basis points depending upon the Leverage Ratio. The Credit Facility contains customary covenants that restrict our ability to incur additional debt; encumber our assets; sell assets; make or enter into certain investments, loans or guaranties, and enter into sale and leaseback arrangements. The Credit Facility also requires us to maintain a consolidated indebtedness ratio (calculated as consolidated indebtedness to consolidated earnings before interest, taxes, depreciation, amortization, certain transaction-related deductions and other non-cash deductions) of 3.5:1.0 or less and an interest coverage ratio (consolidated earnings before interest, taxes, depreciation, amortization, certain transaction-related deductions and other non-cash deductions to consolidated interest expense) of at least 2.5:1.0. We had $240.0 million of borrowings outstanding at March 31, 2018. Based on our Leverage Ratio, we had $252.5 million of available borrowings, net of the outstanding letters of credit, at March 31, 2018.

The Credit Facility has a $40.0 million letter of credit facility. Under the letter of credit facility, the Company pays a fee at a per annum rate equal to the applicable margin for Eurodollar loans in effect from time to time plus a one-time letter of credit fee in an amount equal to 0.125% of the initial stated amount. At March 31, 2018, we had $7.5 million of letters of credit outstanding.

4.500% Senior Unsecured Notes Due 2026

On August 2, 2016, the Company issued $350.0 million aggregate principal amount of 4.500% senior notes (Senior Unsecured Notes) due August 2026. Interest on the Senior Unsecured Notes is payable semi-annually on February 1 and August 1 of each year until all outstanding notes are paid. The Senior Unsecured Notes rank equal to existing and future senior indebtedness, including the Credit Facility and the Private Placement Senior Unsecured Notes. Prior to August 1, 2019, we may redeem with the proceeds of certain equity offerings up to 40% of the original aggregate principal amount of the Senior Unsecured Notes at a redemption price of 104.5% of the principal amount of the notes. On or after August 1, 2019, and prior to August 1, 2021, we may redeem some or all of the Senior Unsecured Notes at a price equal to 100% of the principal amount, plus a make-whole premium. Beginning August 1, 2021, we may redeem some or all of the Senior Unsecured Notes at the redemption prices set forth below (expressed as a percentage of the principal amount being redeemed):

	Percentage
2021		102.25	%
2022		101.50	%
2023		100.75	%
2024 and thereafter		100.00	%

The Senior Unsecured Notes contain covenants that limit our ability and/or our guarantor subsidiaries' ability to create or permit existence of certain liens; enter into sale and leaseback transactions; and consolidate, merge, or transfer all or substantially all of our assets. The Company’s Senior Unsecured Notes are fully, unconditionally, jointly, and severally guaranteed by each of our subsidiaries that are guarantors under the Credit Facility and Private Placement Senior Unsecured Notes. See Footnote (M) to the Unaudited Consolidated Financial Statements for more information on the guarantors of the Senior Unsecured Notes.

Private Placement Senior Unsecured Notes

On October 2, 2007, in a private placement transaction, we entered into a Note Purchase Agreement (the 2007 Note Purchase Agreement) in connection with our sale of $200.0 million of senior unsecured notes, designated as Series 2007A Senior Unsecured Notes (the Series 2007A Senior Unsecured Notes). The Series 2007A Senior Unsecured Notes, which are guaranteed by substantially all of our subsidiaries, were sold at par and issued in four tranches.

At March 31, 2018, the amounts outstanding for each of the remaining tranches are as follows:

		Principal		Maturity Date		Interest Rate
Tranche D		$36.5 million		October 2, 2019			6.48	%

Interest for the Series 2007A Senior Unsecured Notes is payable semi-annually on April 2 and October 2 of each year until all principal is paid for the respective tranche.

Our obligations under the 2007 Note Purchase Agreement are equal in right of payment with all other senior unsecured debt of the Company, including our debt under the Credit Facility and Senior Unsecured Notes. The 2007 Note Purchase Agreement contains customary restrictive covenants, including, but not limited to, covenants that place limits on our ability to encumber our assets, to incur additional debt, to sell assets, or to merge or consolidate with third parties.

The 2007 Note Purchase Agreement requires us to maintain a Consolidated Debt to Consolidated EBITDA (calculated as consolidated indebtedness to consolidated earnings before interest, taxes, depreciation, depletion, amortization, certain transaction-related deductions and other non-cash charges) ratio of 3.50 to 1.00 or less, and to maintain an interest coverage ratio (Consolidated EBITDA to Consolidated Interest Expense [calculated as Consolidated EBITDA, defined above, to consolidated interest expense]) of at least 2.50 to 1.0. In addition, the 2007 Note Purchase Agreement requires the Company to ensure that at all times either (i) Consolidated Total Assets equal at least 80% of the consolidated total assets of the Company and its Subsidiaries, determined in accordance with GAAP, or (ii) Consolidated Total Revenue of the Company and its Restricted Subsidiaries for the period of four consecutive fiscal quarters most recently ended equals at least 80% of the consolidated total revenue of the Company and its Subsidiaries during such period. We were in compliance with all financial ratios and tests at March 31, 2018, and throughout the fiscal year.

Pursuant to a Subsidiary Guaranty Agreement, substantially all of our subsidiaries have guaranteed the punctual payment of all principal, interest, and make-whole amounts (as defined in the 2007 Note Purchase Agreement) on the Series 2007A Senior Unsecured Notes and the other payment and performance obligations of the Company contained in the 2007 Note Purchase Agreement. We are permitted, at our option and without penalty, to prepay from time to time at least 10% of the original aggregate principal amount of the Series 2007A Senior Unsecured Notes at 100% of the principal amount to be prepaid, together with interest accrued on such amount, plus a make-whole amount. The make-whole amount is computed by discounting the remaining scheduled principal and interest payments at a discount rate of 50 basis points above the yield to maturity of U.S. Treasury securities having a maturity equal to the remaining average life of the Series 2007A Senior Unsecured Notes being prepaid.

We lease one of our cement plants from the city of Sugar Creek, Missouri. The city of Sugar Creek issued industrial revenue bonds to partly finance improvements to the cement plant. The lease payments due to the city of Sugar Creek under the cement plant lease, which was entered into upon the sale of the industrial revenue bonds, are equal in amount to the payments required to be made by the city of Sugar Creek to the holders of the industrial revenue bonds. Because we hold all outstanding industrial revenue bonds, no debt is reflected on our financial statements in connection with our lease of the cement plant. Upon expiration of the lease in fiscal 2021, we have the option to purchase the cement plant for a nominal amount.

FAIR VALUE OF FINANCIAL INSTRUMENTS

12 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

FAIR VALUE OF FINANCIAL INSTRUMENTS

(F) Fair Value of Financial Instruments

The fair value of our senior notes has been estimated based upon our current incremental borrowing rates for similar types of borrowing arrangements. The fair value of our Private Placement Senior Unsecured Notes and Senior Unsecured Notes at March 31, 2018 is as follows:

	Fair Value
	(dollars in thousands)
Series 2007A Tranche D		37,849
4.500% Senior Unsecured Notes Due 2026		353,600

The estimated fair value of our long-term debt was based on quoted prices of similar debt instruments with similar terms that are publicly traded (level 2 input). The carrying values of cash and cash equivalents, restricted cash, accounts and notes receivable, accounts payable, and accrued liabilities approximate their fair values at March 31, 2018, due to the short-term maturities of these assets and liabilities. The fair value of our Credit Facility also approximates its carrying value at March 31, 2018.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

BUSINESS SEGMENTS

12 Months Ended

Mar. 31, 2018

Segment Reporting [Abstract]

BUSINESS SEGMENTS

(G) Business Segments

Operating segments are defined as components of an enterprise that engage in business activities that earn revenue, incur expenses, and prepare separate financial information that is evaluated regularly by our chief operating decision maker in order to allocate resources and assess performance.

We are a leading supplier of heavy construction materials, light building materials, and materials used for oil and natural gas extraction in the United States. Our products are commodities that are essential in commercial and residential construction; public construction projects; projects to build, expand, and repair roads and highways; and in oil and natural gas extraction

Our business is organized into three sectors within which there are five reportable business segments. The Heavy Materials sector includes the Cement and Concrete and Aggregates segments. The Light Materials sector includes the Gypsum Wallboard and Recycled Paperboard segments. The Oil and Gas Proppants segment produces frac sand used in oil and gas exploration and extraction.

Our operations are conducted in the U.S. and include the mining of limestone for the manufacture, production, distribution, and sale of portland cement and slag (a basic construction material which is the essential binding ingredient in concrete); the grinding of slag; the mining of gypsum, for the manufacture and sale of gypsum wallboard; the manufacture and sale of recycled paperboard to the gypsum wallboard industry and other paperboard converters; the sale of readymix concrete; and the mining and sale of aggregates (crushed stone, sand, and gravel) and sand used in hydraulic fracturing (frac sand).

We operate seven cement plants, one slag grinding facility, 18 cement distribution terminals, five gypsum wallboard plants, a gypsum wallboard distribution center, a recycled paperboard mill, 17 readymix concrete batch plants, four aggregates processing plants, two frac sand processing facilities, three frac sand drying facilities, and six frac sand trans-load locations. The principal markets for our cement products are Texas, Illinois, the central plains, Michigan, Iowa, the Rocky Mountains, northern Nevada, southern Ohio, and northern California. Gypsum wallboard and recycled paperboard are distributed throughout the continental U.S., with the exception of the Northeast. Concrete and aggregates are sold to local readymix producers and paving contractors in the Austin, Texas area, north of Sacramento, California and the greater Kansas City, Missouri area, while frac sand is currently sold into shale deposits across the United States. Other segment operations that are not material to our business are included in Other.

We conduct one of our seven cement plant operations, Texas Lehigh Cement Company LP, in Buda, Texas, through a Joint Venture. For segment reporting purposes only, we proportionately consolidate our 50% share of the Joint Venture’s Revenue and Operating Earnings, consistent with the way management reports the segments within the Company for making operating decisions and assessing performance.

We account for intersegment sales at market prices. The table below sets forth certain financial information relating to our operations by segment. We do not allocate interest or taxes at the segment level, only at the consolidated company level.

	For the Years Ended March 31,
	2018			2017			2016
	(dollars in thousands)
Revenue -
Cement	$	651,750		$	566,321		$	528,499
Concrete and Aggregates		157,013			154,592			128,073
Gypsum Wallboard		491,779			473,651			461,457
Paperboard		181,742			167,065			149,192
Oil and Gas Proppants		85,496			34,623			57,591
Other		12,748			—			—
		1,580,528			1,396,252			1,324,812
Less: Intersegment Revenue		(88,124	)		(79,116	)		(73,862	)
Less: Joint Venture Revenue		(105,884	)		(105,916	)		(107,458	)
	$	1,386,520		$	1,211,220		$	1,143,492

	For the Years Ended March 31,
	2018		2017		2016
	(dollars in thousands)
Intersegment Revenue -
Cement	$	16,442	$	15,781	$	13,939
Concrete and Aggregates		1,335		1,262		922
Paperboard		70,347		62,073		59,001
	$	88,124	$	79,116	$	73,862
Cement Sales Volume (M tons) -
Wholly Owned		4,453		3,934		3,903
Joint Venture		912		937		875
		5,365		4,871		4,778

	For the Years Ended March 31,
	2018				2017			2016
				(dollars in thousands)
Operating Earnings -
Cement	$	179,151			$	153,525		$	137,854
Concrete and Aggregates		17,854				18,072			9,807
Gypsum Wallboard		158,551				159,866			159,352
Paperboard		32,758				37,601			32,153
Oil and Gas Proppants		(6,423	)			(14,633	)		(68,466	)
Other		284				—			—
Sub-Total		382,175				354,431			270,700
Corporate General and Administrative Expense		(41,205	)			(33,940	)		(37,193	)
Legal Settlements		(45,098	)			—			—
Other Non-Operating Income		3,728				2,139			2,328
Acquisition and Litigation Expense		—				(5,480	)		—
Earnings Before Interest and Income Taxes		299,600				317,150			235,835
Interest Expense, net		(27,638	)			(22,631	)		(16,583	)
Earnings Before Income Taxes	$	271,962			$	294,519		$	219,252
Cement Operating Earnings -
Wholly Owned	$	135,732			$	111,139		$	98,771
Joint Ventures		43,419				42,386			39,083
	$	179,151			$	153,525		$	137,854
Capital Expenditures -
Cement	$	45,088			$	32,790		$	20,262
Concrete and Aggregates		4,977				6,528			18,783
Gypsum Wallboard		19,382				11,393			4,832
Paperboard		5,177				3,996			5,542
Oil and Gas Proppants		56,872				1,534			40,144
Other, net		461				697			—
	$	131,957			$	56,938		$	89,563
Depreciation, Depletion and Amortization -
Cement	$	50,891			$	36,727		$	33,400
Concrete and Aggregates		7,931				7,931			6,260
Gypsum Wallboard		18,179				18,728			19,988
Paperboard		8,694				8,425			8,312
Oil and Gas Proppants		25,687				18,255			27,227
Corporate and Other		2,633				1,725			1,918
	$	114,015			$	91,791		$	97,105

	As of March 31,
	2018		2017		2016
	(dollars in thousands)
Identifiable Assets
Cement	$	1,247,504	$	1,234,617	$	819,994
Concrete and Aggregates		104,851		110,413		106,634
Gypsum Wallboard		386,041		379,414		392,523
Paperboard		123,819		124,356		127,371
Oil and Gas Proppants		401,421		376,306		409,497
Other, net		104,367		22,018		27,616
	$	2,368,003	$	2,247,124	$	1,883,635

Segment Operating Earnings, including the proportionately consolidated 50% interest in the revenue and expenses of the Joint Venture, represent Revenue less direct operating expenses, segment Depreciation, and segment Selling, General, and Administrative expenses. We account for intersegment sales at market prices. Corporate assets consist primarily of cash and cash equivalents, general office assets, miscellaneous other assets and assets acquired in the Wildcat Acquisition.

The basis used to disclose Identifiable Assets; Capital Expenditures; and Depreciation, Depletion, and Amortization conforms with the equity method, and is similar to how we disclose these accounts in our Consolidated Balance Sheets and Consolidated Statements of Earnings.

The segment breakdown of Goodwill at March 31, 2018 and 2017 is as follows:

	For the Years Ended March 31,
	2018		2017
	(dollars in thousands)
Cement	$	74,214	$	74,214
Gypsum Wallboard		116,618		116,618
Paperboard		7,538		7,538
Corporate and Other		6,841		—
	$	205,211	$	198,370

Summarized financial information for the Joint Venture that is not consolidated is set out below (this summarized financial information includes the total amount for the Joint Venture and not our 50% interest in those accounts):

	For the Years Ended March 31,
	2018		2017
	(dollars in thousands)
Revenue	$	216,533	$	215,569
Gross Margin	$	91,647	$	90,098
Earnings Before Income Taxes	$	86,838	$	84,772

	March 31, 2018		March 31, 2017
	(dollars in thousands)
Current Assets	$	71,089	$	73,767
Non-Current Assets	$	66,856	$	42,337
Current Liabilities	$	20,671	$	22,293

INCOME TAXES

12 Months Ended

Mar. 31, 2018

Income Tax Disclosure [Abstract]

INCOME TAXES

(H) Income Taxes

The provision for income taxes includes the following components:

	For the Years Ended March 31,
	2018			2017			2016
	(dollars in thousands)
Current Provision (Benefit) -
Federal	$	58,695		$	86,459		$	64,256
State		5,989			7,638			4,727
		64,684			94,097			68,983
Deferred Provision (Benefit) -
Federal		(52,333	)		7,274			(546	)
State		2,979			(5,071	)		(1,777	)
		(49,354	)		2,203			(2,323	)
Provision for Income Taxes	$	15,330		$	96,300		$	66,660

The effective tax rates vary from the federal statutory rates due to the following items:

	For the Years Ended March 31,
	2018			2017			2016
	(dollars in thousands)
Earnings Before Income Taxes	$	271,962		$	294,519		$	219,252
Income Taxes at Statutory Rate	$	85,804		$	103,082		$	76,738
Increases (Decreases) in Tax Resulting from -
State Income Taxes, net		6,139			1,668			1,166
Statutory Depletion in Excess of Cost		(6,341	)		(1,216	)		(5,672	)
Domestic Production Activities Deduction		(5,995	)		(7,615	)		(6,302	)
Excess Tax Benefit from Stock Compensation		(4,129	)		—			—
Meals and Entertainment Disallowance		567			626			629
Limitation on Officer's Compensation		246			—			—
Impact of Tax Cuts and Jobs Act of 2017		(61,692	)		—			—
Other		731			(245	)		101
Provision for Income Taxes	$	15,330		$	96,300		$	66,660
Effective Tax Rate		6	%		33	%		30	%

Components of deferred income taxes are as follows:

	March 31,
	2018			2017
	(dollars in thousands)
Items Giving Rise to Deferred Tax Liabilities -
Excess Tax Depreciation and Amortization	$	(106,367	)	$	(161,204	)
Depletion		(11,069	)		(18,638	)
State Income Taxes, net		(14,265	)		(11,455	)
Other		(5,957	)		(8,515	)
Total Deferred Tax Liabilities	$	(137,658	)	$	(199,812	)
Items Giving Rise to Deferred Tax Assets -
Change in Accruals	$	8,965		$	12,992
Inventory		4,276			1,242
Bad Debts		1,891			3,895
Long-term Incentive Compensation Plan		4,616			8,691
Credits and Other Carryforwards		12,879			13,103
Pension		1,108			4,178
Other		—			218
Subtotal		33,735			44,319
Valuation Allowance		(15,043	)		(10,531	)
Total Deferred Tax Assets	$	18,692		$	33,788

We have state income tax net operating loss (NOL) carryforwards of $1.5 million which will expire on various dates beginning in 2027. We have state income tax investment credits of $14.9 million which may be carried forward indefinitely.

Uncertain tax position

We are subject to audit examinations at federal, state, and local levels by tax authorities in those jurisdictions who may challenge the treatment or reporting of any return item. The tax matters challenged by the tax authorities are typically complex; therefore, the ultimate outcome of these challenges is subject to uncertainty. There were no uncertain tax positions at March 31, 2018, 2017, and 2016.

Tax Cuts and Jobs Act

The Tax Cuts and Jobs Act (the Tax Act) reduced the federal corporate tax rate to 21.0% effective January 1, 2018. In accordance with Section 15 of the Internal Revenue Code, we utilized a blended rate of 31.55% for our fiscal 2018 tax year, by applying a prorated percentage of the number of days prior to and subsequent to the January 1, 2018 effective date.

On December 22, 2017, the SEC issued Staff Accounting Bulletin (SAB 118), which provides guidance on accounting for tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. We recorded a provisional benefit for the re-measurement of the deferred tax liabilities of $61.0 million to our income tax expense during the quarter ended December 31, 2017. During the quarter ended March 31, 2018, we updated our estimate of the impact of the Tax Act under ASC 740 and recorded an additional benefit of $0.7 million resulting in a total estimated benefit of $61.7 million for the fiscal 2018 tax year.

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Mar. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

(I) Commitments and Contingencies

Our operations and properties are subject to extensive and changing federal, state and local laws, regulations and ordinances governing the protection of the environment, as well as laws relating to worker health and workplace safety. We carefully consider the requirements mandated by such laws and regulations and have procedures in place at all of our operating units to monitor compliance. Any matters which are identified as potential exposures under these laws and regulations are carefully reviewed by management to determine our potential liability. Although management is not aware of any exposures which require an accrual under generally accepted accounting principles, there can be no assurance that prior or future operations will not ultimately result in violations, claims or other liabilities associated with these regulations.

We have certain deductible limits under our workers’ compensation and liability insurance policies for which reserves are established based on the undiscounted estimated costs of known and anticipated claims. We have entered into standby letter of credit agreements relating to workers’ compensation and auto and general liability self-insurance. At March 31, 2018, we had contingent liabilities under these outstanding letters of credit of approximately $7.5 million.

We are currently contingently liable for performance under $26.1 million in performance bonds required by certain states and municipalities, and their related agencies. The bonds are principally for certain reclamation obligations and mining permits. We have indemnified the underwriting insurance company against any exposure under the performance bonds. In our past experience, no material claims have been made against these financial instruments.

Domestic Wallboard Antitrust Litigation

Since late December 2012, several purported class action lawsuits were filed in various United States District Courts, including the Eastern District of Pennsylvania, Western District of North Carolina and the Northern District of Illinois, against the Company’s subsidiary, American Gypsum Company LLC (American Gypsum), alleging that the defendant wallboard manufacturers conspired to fix the price for drywall sold in the United States in violation of federal antitrust laws and, in some cases related provisions of state law. The complaints alleged that the defendant wallboard manufacturers conspired to increase prices through the announcement and implementation of coordinated price increases, output restrictions, and other restraints of trade, including the elimination of individual “job quote” pricing. In addition to American Gypsum, the defendants in these lawsuits included CertainTeed Corp. (CertainTeed), USG Corporation and United States Gypsum (together USG), New NGC, Inc. (New NGC), Lafarge North America (Lafarge), Temple Inland Inc. (TIN) and PABCO Building Products LLC (PABCO). On April 8, 2013, the Judicial Panel on Multidistrict Litigation (JPML) transferred and consolidated all related cases to the Eastern District of Pennsylvania for coordinated pretrial proceedings.

On June 24, 2013, the direct and indirect purchaser plaintiffs filed consolidated amended class action complaints. The direct purchasers’ complaint added the Company as a defendant. The plaintiffs in the consolidated class action complaints assert claims on behalf of purported classes of direct purchasers or end users of wallboard from January 1, 2012 to the present for unspecified monetary damages (including treble damages) and in some cases injunctive relief. On July 29, 2013, the Company and American Gypsum answered the complaints, denying all allegations that they conspired to increase the price of drywall and asserting affirmative defenses to the plaintiffs’ claims.

In 2014, USG and TIN entered into agreements with counsel representing the direct and indirect purchaser classes pursuant to which they agreed to settle all claims against them. Under the terms of its settlement agreement, USG agreed to pay $48.0 million to resolve the direct and indirect purchaser class actions. In its settlement agreement, TIN agreed to pay $7.0 million to resolve the direct and indirect purchaser class actions. On August 20, 2015, the court entered orders finally approving USG and TIN’s settlements with the direct and indirect purchaser plaintiffs. Following completion of the initial discovery, the Company and remaining co-defendants moved for summary judgment. On February 18, 2016, the court denied the Company’s motion for summary judgment and granted judgment in favor of CertainTeed. On June 16, 2016, Lafarge entered into an agreement with counsel for the direct purchaser class under which it agreed to settle all claims against it for $23.0 million. The court entered an order finally approving this settlement on December 7, 2016. On July 28, 2016, Lafarge entered into an agreement with counsel representing the indirect purchaser class under which it agreed to settle all claims against it for $5.2 million, which was approved by the court on February 28, 2017. On July 14, 2016, the Company’s motion for permission to appeal the summary judgment decision to the U.S. Court of Appeals for the Third Circuit was denied.

Direct purchaser plaintiffs and indirect purchaser plaintiffs filed their motions for class certification on August 3, 2016 and October 12, 2016, respectively. On August 23, 2017, the court granted the direct purchaser plaintiffs’ motion for class certification and certified a class consisting of all persons or entities that purchased paper-backed gypsum wallboard in the United States from January 1, 2012 through January 31, 2013 directly from American Gypsum, the Company, Lafarge, New NGC, PABCO, USG, and/or L&W Supply Corporation (which was a subsidiary of USG Corporation during the class period). On September 6, 2017, American Gypsum, the Company, New NGC, and PABCO filed a petition with the U.S. Court of Appeals for the Third Circuit seeking interlocutory appeal of the district court’s decision granting the direct purchaser plaintiffs’ motion for class certification under Federal Rule of Civil Procedure 23(f). The Third Circuit denied the Defendant’s petition on October 27, 2017. On August 24, 2017, the court denied the indirect purchaser plaintiffs’ motion for class certification. On September 7, 2017, the indirect purchaser plaintiffs filed a petition with the Third Circuit appealing the district court’s denial of their motion for class certification. The Third Circuit denied the indirect purchaser plaintiff’s petition on October 12, 2017.

On December 29, 2017 American Gypsum and the Company, as well as New NGC and PABCO, which are not affiliated with the Company, entered into a settlement agreement (the Direct Purchaser Settlement Agreement) with counsel representing the direct purchaser class to settle all claims made against the Company, American Gypsum, New NGC and PABCO in the direct purchaser class action. The Direct Purchaser Settlement Agreement, in which the Company and American Gypsum deny all wrongdoing, also includes releases by the participating class members of the Company and American Gypsum as well as their subsidiaries, affiliates, and other related parties, for the time period from January 1, 2012 through the date of execution of the Direct Purchaser Settlement Agreement. The Direct Purchaser Settlement Agreement grants the Company, American, New NGC, and PABCO the right to terminate the Direct Purchaser Settlement Agreement in the event an agreed upon percentage of potential class members opt-out of the Direct Purchaser Settlement Agreement. Additionally, the Direct Purchaser Settlement Agreement is conditioned on final approval of the District Court. On January 5, 2018 American Gypsum, New NGC, and PABCO entered into a settlement agreement (the Indirect Purchaser Settlement Agreement) with counsel representing the indirect purchaser class to settle all claims against American Gypsum, New NGC and PABCO in the indirect purchaser class action. The Indirect Purchaser Settlement Agreement is conditioned on final approval of the District Court. Under the Direct and Indirect Purchaser Settlement Agreements, the Company and American Gypsum agreed to pay a total of approximately $39.1 million in cash to settle the claims against them. At December 31, 2017 we accrued the total amount of these two settlements. During March 2018, we deposited approximately $38.8 million into a qualified settlement fund. Upon final approval of the District Court, these funds will be transferred to the plaintiffs. We expect to receive approval from the District Court by the end of calendar 2018.

On March 17, 2015, a group of homebuilders filed a complaint against the defendants, including American Gypsum, based upon the same conduct alleged in the consolidated class action complaints. On March 24, 2015, the JPML transferred this action to the multidistrict litigation already pending in the Eastern District of Pennsylvania. Following the transfer, the homebuilder plaintiffs filed two amended complaints, on December 14, 2015 and March 25, 2016. As a result of settlements reached with TIN and Lafarge, the homebuilder plaintiffs voluntarily dismissed their claims against TIN and Lafarge on June 6 and June 24, 2016, respectively. On January 31, 2017, the plaintiffs voluntarily dismissed their claims against CertainTeed. Effective May 8, 2018, American Gypsum and the homebuilder plaintiffs entered into a settlement agreement (the Homebuilder Settlement Agreement) to settle all claims made against American Gypsum. The Homebuilder Settlement Agreement, in which American Gypsum denies all wrongdoing, includes releases by the homebuilder plaintiffs of American Gypsum as well as its subsidiaries, affiliates, and other related parties, for the time period prior to and including the date of execution of the Homebuilder Settlement Agreement. Under the Homebuilder Settlement Agreement, American Gypsum agreed to pay a total of $6.0 million in cash to settle the claims against it. At March 31, 2018 we accrued the total amount of this settlement and this amount was paid on May 18, 2018.

In June 2015, American Gypsum and an employee received grand jury subpoenas from the United States District Court for the Western District of North Carolina seeking information regarding an investigation of the gypsum drywall industry by the Antitrust Division of the Department of Justice. We believe the investigation, although a separate proceeding, is related to the same subject matter at issue in the litigation described above and we intend to fully cooperate with government officials. Given its preliminary nature, we are currently unable to determine the ultimate outcome of such investigation.

Other

In the ordinary course of business, we execute contracts involving indemnifications that are standard in the industry and indemnifications specific to a transaction such as the sale of a business. These indemnifications might include claims relating to any of the following: environmental and tax matters; intellectual property rights; governmental regulations and employment-related matters; customer, supplier, construction contractor and other commercial contractual relationships; and financial matters. While the maximum amount to which we may be exposed under such agreements cannot be estimated, it is the opinion of management that these indemnifications are not expected to have a material adverse effect on the Company’s consolidated financial position, results of operations or cash flows. We currently have no outstanding guarantees of third party debt.

We have certain forward purchase contracts, primarily for natural gas, that expire during calendar 2017. The contracts are for approximately 25% of our anticipated natural gas usage.

We have certain operating leases covering manufacturing, transportation, a quarry and certain other facilities and equipment. Rental expense for fiscal years 2018, 2017, and 2016 totaled $12.0 million, $11.3 million and $10.3 million, respectively. Minimum annual rental commitments as of March 31, 2018, under noncancelable leases are set forth as follows (dollars in thousands):

Fiscal Year	Amount
2019	$	11,386
2020	$	8,235
2021	$	4,807
2022	$	3,359
2023	$	2,979
Thereafter	$	5,596

STOCK OPTION PLANS

12 Months Ended

Mar. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

STOCK OPTION PLANS

(J) Stock Option Plans

On August 7, 2013, our stockholders approved the Eagle Materials Inc. Amended and Restated Incentive Plan (the Plan), which increased the shares we are authorized to issue as awards by 3,000,000 (1,500,000 of which may be stock awards). Under the terms of the Plan, we may issue equity awards, including stock options, restricted stock units (RSUs), restricted stock, and stock appreciation rights to employees of the Company and members of the Board of Directors. Awards that were already outstanding prior to the approval of the Plan on August 7, 2013, remain outstanding. The Compensation Committee of our Board of Directors specifies the terms for grants of equity awards under the Plan.

Long-Term Compensation Plans

Options

In May 2017, the Compensation Committee of the Board of Directors approved the granting to certain officers and key employees of an aggregate of 58,055 performance vesting stock options that are earned only if certain performance conditions are satisfied (the Fiscal 2018 Employee Performance Stock Option Grant). The performance criterion for the Fiscal 2018 Employee Performance Stock Option Grant is based upon the achievement of certain levels of return on equity (as defined in the option agreements), ranging from 11.0% to 18.0%, for the fiscal year ending March 31, 2018. All stock options will be earned if the return on equity is 18.0% or greater, and the percentage of shares earned will be reduced proportionately to approximately 66.7% if the return on equity is 11.0%. If the Company does not achieve a return on equity of at least 11.0%, all stock options granted will be forfeited. During fiscal 2018, the adjusted return on equity was approximately 17.2%; therefore, 55,858 options were earned, with the remaining options forfeited. The earned stock options will lapse ratably over four years, with the first fourth lapsing promptly following the determination date, and the remaining options vesting on March 31, 2019 through 2021. The stock options have a term of 10 years from the date of grant. The Compensation Committee also approved the granting of 48,379 time-vesting stock options to the same officers and key employees, which vest ratably over a four-year period (the Fiscal 2018 Employee Time Vesting Stock Option Grant). The stock options have a term of 10 years from the date of grant. In August 2017, we granted to members of the Board of Directors 6,052 stock options (the Fiscal 2018 Board of Directors Stock Option Grant). Stock options granted under the Fiscal 2018 Board of Directors Stock Option Grant vest immediately and can be exercised from the date of grant until their expiration on the tenth anniversary of the date of grant. The Fiscal 2018 Employee Performance Stock Option Grant, the Fiscal 2018 Employee Time Vesting Stock Option Grant, and Fiscal 2018 Board of Directors Stock Option Grant were valued at the grant date using the Black-Scholes option pricing model.

All stock options issued during fiscal 2018 and 2017 were valued at the grant date using the Black-Scholes option pricing model. The weighted-average assumptions used in the Black-Scholes model to value the option awards in fiscal 2018 and 2017 are as follows:

	2018			2017
Dividend Yield		1.3	%		1.3	%
Expected Volatility		36.3	%		36.5	%
Risk Free Interest Rate		2.10	%		1.40	%
Expected Life	6.0 years			6.0 years

Stock option expense for all outstanding stock option awards was approximately $4.3 million, $5.3 million, and $7.5 million, for the years ended March 31, 2018, 2017, and 2016, respectively. At March 31, 2018, there was approximately $6.8 million of unrecognized compensation cost related to outstanding stock options which is expected to be recognized over a weighted-average period of 2.5 years.

The following table shows stock option activity for the years presented:

	For the Years Ended March 31,
	2018					2017					2016
	Number of Shares			Weighted Average Exercise Price		Number of Shares			Weighted Average Exercise Price		Number of Shares			Weighted Average Exercise Price
Outstanding Options at Beginning of Year		1,323,379		$	66.07		1,817,763		$	53.03		1,665,565		$	46.37
Granted		119,986		$	100.20		202,364		$	77.76		318,572		$	79.83
Exercised		(448,295	)	$	60.27		(677,566	)	$	34.46		(137,874	)	$	27.58
Cancelled		(36,934	)	$	79.97		(19,182	)	$	70.30		(28,500	)	$	86.35
Outstanding Options at End of Year		958,136		$	72.52		1,323,379		$	66.07		1,817,763		$	53.03
Options Exercisable at End of Year		651,218					874,116					1,285,412
Weighted Average Fair Value of Options Granted during the Year				$	33.37				$	25.22				$	24.27

The following table summarizes information about stock options outstanding at March 31, 2018:

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number of Shares Outstanding		Weighted Average Remaining Contractual Life		Weighted Average Exercise Price		Number of Shares Outstanding		Weighted Average Exercise Price
$23.17 - $29.84		65,912		3.35	$	23.27		65,912	$	23.27
$33.43 - $37.34		99,582		4.21	$	33.94		99,582	$	33.94
$53.22 - $77.67		307,424		7.00	$	71.12		183,248	$	69.79
$79.73 - $106.00		485,218		7.37	$	88.02		302,476	$	84.72
		958,136		6.65	$	72.52		651,218	$	66.53

At March 31, 2018, the aggregate intrinsic value for outstanding and exercisable options was approximately $29.3 million, and $23.8 million, respectively. The total intrinsic value of options exercised during the fiscal year ended March 31, 2018 was approximately $18.7 million.

Restricted Stock

In May 2017, the Compensation Committee approved the granting to certain officers and key employees an aggregate of 52,646 shares of performance vesting restricted stock that will be earned if certain performance conditions are satisfied (the Fiscal 2018 Employee Restricted Stock Performance Award). The performance criterion for the Fiscal 2018 Employee Restricted Stock Performance Award is based upon the achievement of certain levels of return on equity (as defined in the agreement), ranging from 11.0% to 18.0%, for the fiscal year ended March 31, 2018. All restricted shares will be earned if the return on equity is 18.0% or greater, and the percentage of shares earned will be reduced proportionately to approximately 66.7% if the return on equity is 11.0%. If the Company does not achieve a return on equity of at least 11.0%, all awards will be forfeited. During fiscal 2018, the adjusted return on equity was approximately 17.2%; therefore approximately 50,656 shares were earned, with the remaining shares forfeited. Restrictions on the earned shares will lapse ratably over four years, with the first fourth lapsing promptly following the determination date and the remaining restrictions lapsing on March 31, 2019 through 2021. The Compensation Committee also approved the granting of 43,874 shares of time vesting restricted stock to the same officers and key employees, which vest ratably over four years (the Fiscal 2018 Employee Restricted Stock Time Vesting Award). Both of the Fiscal 2018 Employee Restricted Stock Performance Award and the Fiscal 2018 Employee Restricted Stock Time Vesting Award were valued at the closing price of the stock on the date of grant and are being expensed over a four-year period. In August 2017, we granted to members of the Board of Directors 11,444 shares of restricted stock (the Board of Directors Fiscal 2018 Restricted Stock Award) which vested six months after the grant date. The Board of Director Fiscal 2018 Restricted Stock Awards were valued at the closing price of the stock on the date of the grant and were expensed over a six-month period.

The fair value of restricted stock is estimated based on the stock price at the date of the grant. The following table summarizes the activity for nonvested restricted shares during the fiscal year ended March 31, 2018:

	Number of Shares			Weighted Average Grant Date Fair Value
Restricted Stock Beginning of Year		371,213		$	60.33
Granted		107,964		$	100.05
Vested		(119,187	)	$	80.04
Forfeited		(31,931	)	$	40.00
Nonvested Restricted Stock at End of Year		328,059		$	65.76

During fiscal 2017 and 2016, the weighted average grant date fair value of restricted shares granted was $76.67 and $81.30, respectively.

Expense related to restricted shares was $9.6 million, $6.8 million, and $9.8 million in fiscal years ended March 31, 2018, 2017, and 2016, respectively. At March 31, 2018, there were approximately 330,000 shares with remaining restrictions, for which $17.0 million of unearned compensation will be recognized over a weighted-average period of 2.3 years.

The number of shares available for future grants of stock options, restricted stock units, stock appreciation rights, and restricted stock under the Plan was 4,176,195 at March 31, 2018. Of the available shares, a total of 1,386,296 can be used for future restricted stock and restricted stock unit grants.

NET INTEREST EXPENSE

12 Months Ended

Mar. 31, 2018

Banking And Thrift Interest [Abstract]

NET INTEREST EXPENSE

(K) Net Interest Expense

The following components are included within Interest Expense, net:

	For the Years Ended March 31,
	2018			2017			2016
	(dollars in thousands)
Interest Income	$	(14	)	$	(40	)	$	(6	)
Interest Expense		26,433			21,595			15,891
Other Expenses		1,219			1,076			698
Interest Expense, net	$	27,638		$	22,631		$	16,583

Interest Income includes interest earned on investments of excess cash. Components of Interest Expense include interest associated with the Credit Facility, Senior Unsecured Notes, Private Placement Senior Unsecured Notes, and commitment fees based on the unused portion of the Credit Facility. Other Expenses include amortization of debt issuance costs, and bank credit facility costs.

PENSION AND PROFIT SHARING PLANS

12 Months Ended

Mar. 31, 2018

Compensation And Retirement Disclosure [Abstract]

PENSION AND PROFIT SHARING PLANS

(L) Pension and Profit Sharing Plans

We offer our employees multiple retirement and profit sharing plans.

Pension Plans

We have several defined benefit and defined contribution retirement plans which together cover substantially all of our employees. Benefits paid under the defined benefit plans covering certain hourly employees are based on years of service and each employee’s qualifying compensation over the last few years of employment. Our funding policy is to generally contribute amounts that are deductible for income tax purposes. The annual measurement date is March 31 for the benefit obligations, fair value of plan assets, and the funded status of the defined benefit plans.

The following table provides a reconciliation of the obligations and fair values of plan assets for all defined benefit plans over the two-year period ended March 31, 2018, and a statement of the funded status as of March 31, 2018 and 2017:

	For the Years Ended March 31,
	2018			2017
	(dollars in thousands)
Reconciliation of Benefit Obligations -
Benefit Obligation at April 1,	$	40,589		$	42,281
Service Cost - Benefits Earned During the Period		710			1,001
Interest Cost on Projected Benefit Obligation		1,466			1,584
Amendments		—			199
Actuarial (Gain) Loss		(4,505	)		(3,531	)
Settlement		(3,857	)		—
Benefits Paid		(1,033	)		(945	)
Benefit Obligation at March 31,	$	33,370		$	40,589
Reconciliation of Fair Value of Plan Assets -
Fair Value of Plan Assets at April 1,	$	26,410		$	21,424
Actual Return on Plan Assets		2,805			2,522
Employer Contributions		9,087			3,409
Settlement		(3,857	)		—
Benefits Paid		(1,033	)		(945	)
Fair Value of Plans at March 31,		33,412			26,410
Funded Status -
Funded (Unfunded) Status at March 31,	$	42		$	(14,179	)
Amounts Recognized in the Balance Sheet Consist of -
Prepaid and Other Assets	$	538		$	—
Accrued Benefit Liability		(496	)		(14,179	)
Accumulated Other Comprehensive Losses:
Net Actuarial Loss		5,198			11,587
Prior Service Cost		80			349
Accumulated Other Comprehensive Losses	$	5,278		$	11,936
Reclassification to Retained Earnings		978			—
Tax impact		(2,244	)		(4,540	)
Accumulated Other Comprehensive Losses, net of tax	$	4,012		$	7,396

The table below summarizes the Company’s Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets at March 31, 2018 and 2017:

	March 31,
	2018		2017
	(dollars in thousands)
Projected Benefit Obligation	$	33,370	$	40,589
Accumulated Benefit Obligation	$	33,367	$	40,391
Fair Value of Plan Assets	$	33,412	$	26,410

Net periodic pension cost for the fiscal years ended March 31, 2018, 2017, and 2016, included the following components:

	For the Years Ended March 31,
	2018			2017			2016
	(dollar in thousands)
Service Cost - Benefits Earned During the Period	$	710		$	1,001		$	1,039
Interest Cost of Projected Benefit Obligation		1,466			1,584			1,525
Expected Return on Plan Assets		(2,137	)		(1,606	)		(1,751	)
Recognized Net Actuarial Loss		566			1,712			1,773
Amortization of Prior-Service Cost		269			359			300
Settlement		649			—			—
Net Periodic Pension Cost	$	1,523		$	3,050		$	2,886

During the fourth quarter of fiscal 2018, we offered to pay our deferred vested participants that no longer worked for the Company but were not yet retired. We paid approximately $3.9 million to these participants in March 2018. In connection with this payment, we recognized a settlement cost of approximately $0.6 million.

Expected benefit payments over the next five years, and the following five years under the pension plans are expected to be as follows (dollars in thousands):

Fiscal Years	Total
2019	$	1,350
2020	$	1,416
2021	$	1,520
2022	$	1,604
2023	$	1,657
2024-2028	$	9,412

The following tables set forth the assumptions used in the actuarial calculations of the present value of Net Periodic Benefit Costs and Benefit Obligations:

	March 31,
	2018			2017			2016
Net Periodic Benefit Costs -
Discount Rate		4.03	%		3.83	%		3.70	%
Expected Return on Plan Assets		7.50	%		7.50	%		8.00	%
Rate of Compensation Increase		3.50	%		3.50	%		3.50	%

	March 31,
	2018			2017
Benefit Obligations -
Discount Rate		4.12	%		4.03	%
Rate of Compensation Increase		3.50	%		3.50	%

The expected long-term rate of return on plan assets is an assumption reflecting the anticipated weighted-average rate of earnings on the portfolio over the long-term. To determine this rate, we developed estimates of the key components underlying capital asset returns including: market-based estimates of inflation, real risk-free rates of return, yield curve structure, credit risk premiums, and equity risk premiums. We used these components as appropriate to develop benchmark estimates of the expected long-term management approach employed by us.

The pension plans’ approximate weighted-average asset allocation at March 31, 2018 and 2017 and the range of target allocation are as follows:

		Percentage of Plan Assets at March 31,
	Range of Target Allocation	2018			2017
Asset Category -
Equity Securities	40 – 60%		50	%		70	%
Debt Securities	35 – 60%		47	%		27	%
Other	0 – 5%		3	%		3	%
Total			100	%		100	%

Our pension investment strategies have been developed as part of a comprehensive management process that considers the interaction between the assets and liabilities within each plan. These strategies consider not only the expected risk and returns on plan assets, but also the detailed actuarial projections of liabilities as well as plan-level objectives such as projected contributions, expense, and funded status.

The principal pension investment strategies include asset allocation and active asset management. The range of target asset allocations has been determined after giving consideration to the expected returns of each asset class, the expected variability or volatility of the asset class returns over time, and the complementary nature or correlation of the asset classes within the portfolio. Each asset class is actively managed by one or more external money managers with the objective of generating returns, net of management fees, that exceed market-based benchmarks. None of the plans hold any EXP stock.

During March 2018, we changed the asset allocation to reduce our holdings in equity securities and increase our holdings in debt securities. This was done in response to the pension plan being close to fully funded at March 31, 2018. Due to this reallocation, we anticipate our Expected Return on Plan Assets to be approximately 6% for fiscal 2019.

Based on our current actuarial estimates, we anticipate making contributions ranging from approximately $2.5 million to $3.0 million to our defined benefit plans for fiscal year 2018.

The fair values of our defined benefit plans’ consolidated assets by category as of March 31, 2018 and 2017 were as follows:

	March 31,
	2018		2017
	(dollars in thousands)
Equity Securities	$	16,533	$	18,375
Fixed Income Securities		15,799		7,166
Real Estate Funds		163		147
Commodity Linked Funds		213		464
Cash Equivalents		704		258
Total	$	33,412	$	26,410

The fair values of our defined benefit plans’ consolidated assets were determined using the fair value hierarchy of inputs described in Footnote (A) to the Consolidated Financial Statements.

The fair values by category of inputs as of March 31, 2018 were as follows:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Asset Categories	(dollars in thousands)
Equity Securities	$	—	$	16,533	$	—	$	16,533
Fixed Income Securities		—		15,799		—		15,799
Real Estate Funds		—		163		—		163
Commodity Linked Funds		—		213		—		213
Cash Equivalents		704		—		—		704
	$	704	$	32,708	$	—	$	33,412

The fair values by category of inputs as of March 31, 2017 were as follows:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Asset Categories	(dollars in thousands)
Equity Securities	$	—	$	18,375	$	—	$	18,375
Fixed Income Securities		—		7,166		—		7,166
Real Estate Funds		—		147		—		147
Commodity Linked Funds		—		464		—		464
Cash Equivalents		258		—		—		258
	$	258	$	26,152	$	—	$	26,410

Equity securities consist of funds that are not actively traded. These funds are maintained by an investment manager and are primarily invested in indexes. The remaining funds, excluding cash, primarily consist of investments in institutional funds.

Profit Sharing Plans

We also provide profit sharing plans, which cover substantially all salaried and certain hourly employees. The profit sharing plans are defined contribution plans funded by employer discretionary contributions; employees may also contribute a certain percentage of their base annual salary. Employees are fully vested in their own contributions and become fully vested in any Company contributions over a six-year period for salaried employees and a three-year period for hourly employees. Costs relating to the employer discretionary contributions for our contribution plan totaled $8.4 million, $6.4 million, and $6.2 million in fiscal years 2018, 2017, and 2016, respectively.

Individuals who became our employees as a result of a previous transaction are provided benefits substantially comparable to those provided under the seller’s benefit plans. These plans included the seller’s 401(k) plan which allows for employer matching percentages of hourly employees. As a result, we made matching contributions to the hourly profit sharing plan totaling $0.6 million, $0.3 million, and $0.3 million for these employees during fiscal years 2018, 2017, and 2016, respectively.

Approximately sixty of our employees belong to three different multi-employer plans. The collective bargaining agreements for the employees who participate in the multi-employer plans expire in March 2020. Our expense related to these plans was approximately $1.6 million, $1.6 million, and $1.3 million during fiscal years 2018, 2017, and 2016, respectively. We anticipate the total expense in fiscal 2019 related to these plans will be approximately $1.8 million.

FINANCIAL STATEMENTS FOR GUARANTORS OF THE 4.500% SENIOR UNSECURED NOTES

12 Months Ended

Mar. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

FINANCIAL STATEMENTS FOR GUARANTORS OF THE 4.500% SENIOR UNSECURED NOTES

(M) FINANCIAL STATEMENTS FOR GUARANTORS OF THE 4.500% SENIOR UNSECURED NOTES

On August 2, 2016, the Company completed a public offering of its Senior Unsecured Notes. The Senior Unsecured Notes are senior unsecured obligations of the Company and were offered under the Company’s existing shelf registration statement filed with the Securities and Exchange Commission.

The Senior Unsecured Notes are guaranteed by all of the Company’s wholly owned subsidiaries, and all guarantees are full and unconditional, and are joint and several. The following unaudited Condensed Consolidating Financial Statements present separately the Earnings and Comprehensive Earnings, Balance Sheet, and Cash Flows of the parent issuer (Eagle Materials Inc.), and the guarantors (all wholly owned subsidiaries of Eagle Materials Inc.) on a combined basis with eliminating entries (dollars in thousands).

Condensed Consolidating Statement of Earnings and Comprehensive Earnings For the Year Ended March 31, 2018	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
Revenue	$	—		$	1,386,520		$	—		$	1,386,520
Cost of Goods Sold		—			1,047,764			—			1,047,764
Gross Profit		—			338,756			—			338,756
Equity in Earnings of Unconsolidated Joint Venture		43,419			43,419			(43,419	)		43,419
Equity in Earnings of Subsidiaries		289,950			—			(289,950	)		—
Corporate General and Administrative Expenses		(37,825	)		(3,380	)		—			(41,205	)
Legal Settlements		(45,098	)		—			—			(45,098	)
Other Non-Operating Income		(233	)		3,961			—			3,728
Interest Expense, net		(27,609	)		(29	)		—			(27,638	)
Earnings before Income Taxes		222,604			382,727			(333,369	)		271,962
Income Taxes		34,028			(49,358	)		—			(15,330	)
Net Earnings	$	256,632		$	333,369		$	(333,369	)	$	256,632
Net Earnings	$	256,632		$	333,369		$	(333,369	)	$	256,632
Net Actuarial Change in Benefit Plans, net of tax		3,384			3,384			(3,384	)		3,384
Comprehensive Earnings	$	260,016		$	336,753		$	(336,753	)	$	260,016

Condensed Consolidating Statement of Earnings and Comprehensive Earnings For the Year Ended March 31, 2017	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
Revenue	$	—		$	1,211,220		$	—		$	1,211,220
Cost of Goods Sold		—			899,175			—			899,175
Gross Profit		—			312,045			—			312,045
Equity in Earnings of Unconsolidated Joint Venture		42,386			42,386			(42,386	)		42,386
Equity in Earnings of Subsidiaries		210,923			—			(210,923	)		—
Corporate General and Administrative Expenses		(28,545	)		(5,395	)		—			(33,940	)
Other Non-Operating Income		(534	)		2,673			—			2,139
Acquisition-Related Expense		(5,480	)		0			—			(5,480	)
Interest Expense, net		(51,315	)		28,684			—			(22,631	)
Earnings before Income Taxes		167,435			380,393			(253,309	)		294,519
Income Taxes		30,784			(127,084	)		—			(96,300	)
Net Earnings	$	198,219		$	253,309		$	(253,309	)	$	198,219
Net Earnings	$	198,219		$	253,309		$	(253,309	)		198,219
Net Actuarial Change in Benefit Plans, net of tax		4,013			4,013			(4,013	)		4,013
Comprehensive Earnings	$	202,232		$	257,322		$	(257,322	)	$	202,232

Condensed Consolidating Statement of Earnings and Comprehensive Earnings For the Year Ended March 31, 2016	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
Revenue	$	—		$	1,143,492		$	—		$	1,143,492
Cost of Goods Sold		—			911,875			—			911,875
Gross Profit		—			231,617			—			231,617
Equity in Earnings of Unconsolidated Joint Venture		39,083			39,083			(39,083	)		39,083
Equity in Earnings of Subsidiaries		160,018			—			(160,018	)		—
Corporate General and Administrative Expenses		(32,047	)		(5,146	)		—			(37,193	)
Other Non-Operating Income		(398	)		2,726			—			2,328
Interest Expense, net		(39,038	)		22,455			—			(16,583	)
Earnings before Income Taxes		127,618			290,735			(199,101	)		219,252
Income Taxes		24,974			(91,634	)		—			(66,660	)
Net Earnings	$	152,592		$	199,101		$	(199,101	)	$	152,592
Net Earnings	$	152,592		$	199,101		$	(199,101	)	$	152,592
Net Actuarial Change in Benefit Plans, net of tax		658			658			(658	)		658
Comprehensive Earnings	$	153,250		$	199,759		$	(199,759	)	$	153,250

Condensed Consolidating Balance Sheet At March 31, 2018	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
ASSETS
Current Assets -
Cash and Cash Equivalents	$	5,784		$	3,531		$	—		$	9,315
Restricted Cash		38,753			—						38,753
Accounts and Notes Receivable		407			141,278			—			141,685
Inventories		—			258,159			—			258,159
Income Tax Receivable		109,510			—			(103,760	)		5,750
Prepaid and Other Current Assets		665			4,408			—			5,073
Total Current Assets		155,119			407,376			(103,760	)		458,735
Property, Plant, and Equipment -		3,188			2,583,340			—			2,586,528
Less: Accumulated Depreciation		(1,089	)		(990,140	)		—			(991,229	)
Property, Plant and Equipment, net		2,099			1,593,200			-			1,595,299
Notes Receivable		—			115			—			115
Investment in Joint Venture		70			60,488			—			60,558
Investments in Subsidiaries and Receivables from Affiliates		2,718,809			762,340			(3,481,149	)		—
Goodwill and Intangible Assets, net		—			239,342			—			239,342
Other Assets		5,417			8,537			—			13,954
	$	2,881,514		$	3,071,398		$	(3,584,909	)	$	2,368,003
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities-
Accounts Payable	$	5,591		$	67,868		$	—		$	73,459
Accrued Liabilities		67,387			38,483			—			105,870
Income Tax Payable		—			103,760			(103,760	)		—
Current Portion of Long-term Debt		—			—			—			—
Total Current Liabilities		72,978			210,111			(103,760	)		179,329
Long-term Debt		620,922			—			—			620,922
Other Long-term Liabilities		124			30,972			—			31,096
Payables to Affiliates		762,340			5,608,236			(6,370,576	)		—
Deferred Income Taxes		7,460			111,506			—			118,966
Total Liabilities		1,463,824			5,960,825			(6,474,336	)		950,313
Total Stockholders’ Equity		1,417,690			(2,889,427	)		2,889,427			1,417,690
	$	2,881,514		$	3,071,398		$	(3,584,909	)	$	2,368,003

Condensed Consolidating Balance Sheet At March 31, 2017	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
ASSETS
Current Assets -
Cash and Cash Equivalents	$	5,184		$	1,377		$	—		$	6,561
Accounts and Notes Receivable		422			135,891			—			136,313
Inventories		—			252,846			—			252,846
Income Tax Receivable		33,196			—			(33,196	)		—
Prepaid and Other Current Assets		484			4,420			—			4,904
Total Current Assets		39,286			394,534			(33,196	)		400,624
Property, Plant, and Equipment -		2,914			2,436,524			—			2,439,438
Less: Accumulated Depreciation		(937	)		(891,664	)		—			(892,601	)
Property, Plant and Equipment, net		1,977			1,544,860			—			1,546,837
Notes Receivable		—			815			—			815
Investment in Joint Venture		51			48,569			—			48,620
Investments in Subsidiaries and Receivables from Affiliates		5,126,289			3,252,309			(8,378,598	)		—
Goodwill and Intangible Assets, net		—			235,505			—			235,505
Other Assets		5,687			9,036			—			14,723
	$	5,173,290		$	5,485,628		$	(8,411,794	)	$	2,247,124
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities-
Accounts Payable	$	6,687		$	85,506		$	—		$	92,193
Accrued Liabilities		21,043			34,336			—			55,379
Income Tax Payable		733			33,196			(33,196	)		733
Current Portion of Long-term Debt		81,214			—			—			81,214
Total Current Liabilities		109,677			153,038			(33,196	)		229,519
Long-term Debt		605,253			—			—			605,253
Other Long-term Liabilities		189			42,689			—			42,878
Payables to Affiliates		3,252,309			2,825,710			(6,078,019	)		—
Deferred Income Taxes		2,412			163,612			—			166,024
Total Liabilities		3,969,840			3,185,049			(6,111,215	)		1,043,674
Total Stockholders’ Equity		1,203,450			2,300,579			(2,300,579	)		1,203,450
	$	5,173,290		$	5,485,628		$	(8,411,794	)	$	2,247,124

Condensed Consolidating Statement of Cash Flows For the Year Ended March 31, 2018	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	$	(83,947	)	$	421,612		$	—		$	337,665
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment		(142	)		(131,815	)		—			(131,957	)
Investment in Subsidiaries		(36,761	)		—			36,761			—
Acquisition Spending		—			(36,761	)		—			(36,761	)
Net Cash Used in Investing Activities		(36,903	)		(168,576	)		36,761			(168,718	)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase in Credit Facility		15,000			—			—			15,000
Repayment of Senior Notes		(81,214	)		—			—			(81,214	)
Dividends Paid to Stockholders		(19,438	)		—			—			(19,438	)
Purchase and Retirement of Common Stock		(61,078	)		—			—			(61,078	)
Proceeds from Stock Option Exercises		24,264			—			—			24,264
Shares Redeemed to Settle Employee Taxes on Stock Compensation		(4,974	)		—			—			(4,974	)
Intra-entity Activity, net		287,643			(250,882	)		(36,761	)		—
Net Cash Provided by (Used in) Financing Activities		160,203			(250,882	)		(36,761	)		(127,440	)
NET INCREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH		39,353			2,154			—			41,507
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD		5,184			1,377			—			6,561
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	$	44,537		$	3,531		$	—		$	48,068

Condensed Consolidating Statement of Cash Flows For the Year Ended March 31, 2017	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	$	(64,376	)	$	395,974		$	—		$	331,598
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment		(697	)		(56,241	)		—			(56,938	)
Investment in Subsidiaries		(400,488	)		—			400,488			—
Acquisition Spending		—			(400,488	)		—			(400,488	)
Net Cash Used in Investing Activities		(401,185	)		(456,729	)		400,488			(457,426	)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase in Credit Facility		(157,000	)		—			—			(157,000	)
Repayment of Senior Notes		(8,000	)		—			—			(8,000	)
Issuance of Long-term Debt		350,000			—			—			350,000
Payment of Debt Issuance Costs		(6,637	)		—			—			(6,637	)
Dividends Paid to Stockholders		(19,341	)		—			—			(19,341	)
Purchase and Retirement of Common Stock		(60,013	)		—			—			(60,013	)
Proceeds from Stock Option Exercises		22,108			—			—			22,108
Shares Redeemed to Settle Employee Taxes on Stock Compensation		(4,468	)		—			—			(4,468	)
Excess Tax Benefits from Share Based Payment Arrangements		10,349			—			—			10,349
Intra-entity Activity, net		340,240			60,248			(400,488	)		—
Net Cash Provided by (Used in) Financing Activities		467,238			60,248			(400,488	)		126,998
NET INCREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH		1,677			(507	)		—			1,170
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD		3,507			1,884			—			5,391
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	$	5,184		$	1,377		$	—		$	6,561

Condensed Consolidating Statement of Cash Flows For the Year Ended March 31, 2016	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	$	(37,985	)	$	303,752		$	—		$	265,767
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment		—			(89,563	)		—			(89,563	)
Investment in Subsidiaries		(32,427	)		—			32,427			—
Acquisition Spending		—			(32,427	)		—			(32,427	)
Net Cash Used in Investing Activities		(32,427	)		(121,990	)		32,427			(121,990	)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase in Credit Facility		52,000			—			—			52,000
Repayment of Senior Notes		(57,045	)		—			—			(57,045	)
Dividends Paid to Stockholders		(20,020	)		—			—			(20,020	)
Purchase and Retirement of Common Stock		(123,530	)		—			—			(123,530	)
Proceeds from Stock Option Exercises		2,866			—			—			2,866
Shares Redeemed to Settle Employee Taxes on Stock Compensation		(4,273	)		—			—			(4,273	)
Excess Tax Benefits from Share Based Payment Arrangements		4,102			—			—			4,102
Intra-entity Activity, net		216,175			(183,748	)		(32,427	)		—
Net Cash Provided by (Used in) Financing Activities		70,275			(183,748	)		(32,427	)		(145,900	)
NET INCREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH		(137	)		(1,986	)		—			(2,123	)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD		3,644			3,870			—			7,514
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	$	3,507		$	1,884		$	—		$	5,391

QUARTERLY RESULTS (UNAUDITED)

12 Months Ended

Mar. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

QUARTERLY RESULTS (UNAUDITED)

(N) Quarterly Results (unaudited)

	For the Years Ended March 31,
	2018		2017
	(dollars in thousands, except per share data)
First Quarter -
Revenue	$	366,121	$	297,504
Gross Profit		86,059		71,955
Earnings Before Income Taxes		79,530		67,276
Net Earnings		54,882		45,344
Diluted Earnings Per Share	$	1.13	$	0.93
Second Quarter -
Revenue	$	376,315	$	332,658
Gross Profit		96,754		91,210
Earnings Before Income Taxes		92,319		89,373
Net Earnings		63,362		60,237
Diluted Earnings Per Share	$	1.31	$	1.25
Third Quarter -
Revenue	$	359,371	$	302,395
Gross Profit		94,566		87,380
Earnings Before Income Taxes		51,388		83,689
Net Earnings		101,380		56,387
Diluted Earnings Per Share	$	2.08	$	1.17
Fourth Quarter -
Revenue	$	284,713	$	278,663
Gross Profit		61,377		61,500
Earnings Before Income Taxes		48,725		54,181
Net Earnings		37,008		36,251
Diluted Earnings Per Share	$	0.76	$	0.75

The fourth quarter of fiscal 2018 included a $6.0 million pre-tax expense related to the Homebuilder Settlement Agreement and $4.0 million of personnel-related expenses, including an increased contribution to the profit sharing plan and a pension settlement expense.

The fourth quarter of fiscal 2017 was adversely affected by approximately $4.4 million of costs related to the completion of the Fairborn Acquisition. Additionally, our fourth quarter 2017 Cement earnings were negatively affected by approximately $5.0 million of annual maintenance costs at our Fairborn plant, as well as the impact of purchase accounting on our inventory costs.

SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

Cash and Cash Equivalents

Cash equivalents include short-term, highly liquid investments with original maturities of three months or less and are recorded at cost, which approximates market value.

Restricted Cash

Accounts and Notes Receivable

Inventories

Inventories are stated at the lower of average cost (including applicable material, labor, depreciation, and plant overhead) or market. Inventories consist of the following:

	March 31,
	2018		2017
	(dollars in thousands)
Raw Materials and Materials-in-Progress	$	121,628	$	122,736
Finished Cement		24,089		24,428
Aggregates		7,787		7,686
Gypsum Wallboard		8,477		7,951
Paperboard		8,602		8,635
Frac Sand		1,696		2,907
Repair Parts and Supplies		79,878		73,732
Fuel and Coal		6,002		4,771
	$	258,159	$	252,846

During fiscal 2017, we wrote down approximately $7.7 million of raw materials and $0.8 million of materials-in-process and frac sand. These inventories are tied to our Oil and Gas Proppants sector.

Property, Plant and Equipment

Property, Plant, and Equipment


Plants		20 to 30 years
Buildings		20 to 40 years
Machinery and Equipment		3 to 25 years

Impairment or Disposal of Long-Lived and Intangible Assets

Goodwill and Intangible Assets

Goodwill

Intangible Assets

Intangible Assets, including the impact of the impairment charges discussed above, at March 31, 2018 and 2017, consist of the following:

	March 31, 2018
	Amortization Period	Cost		Accumulated Amortization			Net
	(dollars in thousands)
Goodwill and Intangible Assets:
Customer Contracts and Relationships	15 years	$	72,260	$	(58,732	)	$	13,528
Sales Contracts	4 years		2,500		(2,500	)		—
Permits	40 years		28,640		(8,037	)		20,603
Goodwill			205,211		—			205,211
Total Goodwill and Intangible Assets		$	308,611	$	(69,269	)	$	239,342

	March 31, 2017
	Amortization Period	Cost		Accumulated Amortization			Net
	(dollars in thousands)
Goodwill and Intangible Assets:
Customer Contracts and Relationships	15 years	$	72,260	$	(56,303	)	$	15,957
Sales Contracts	4 years		2,500		(2,500	)	$	—
Permits	40 years		28,440		(7,262	)	$	21,178
Goodwill			198,370		—		$	198,370
Total Goodwill and Intangible Assets		$	301,570	$	(66,065	)	$	235,505

At March 31, 2018, approximately $1.6 million of customer contracts and relationships were related to our Oil and Gas Proppants sector.

Other Assets

Other Assets are primarily composed of financing costs related to our revolving credit facility, deferred expenses, and deposits.

Income Taxes

Stock Repurchases

Revenue Recognition

Comprehensive Income/Losses

Consolidated Cash Flows - Supplemental Disclosures

Consolidated Cash Flows – Supplemental Disclosures

Interest payments made during the years ended March 31, 2018, 2017, and 2016 were $28.9 million, $19.0 million, and $16.9 million, respectively.

We made net payments of $69.4 million, $76.1 million, and $63.9 million for federal and state income taxes in the years ended March 31, 2018, 2017, and 2016, respectively.

Statements of Consolidated Earnings - Supplemental Disclosures

Statements of Consolidated Earnings – Supplemental Disclosures

Selling, General and Administrative Expenses

Total Selling, General, and Administrative expenses for each of the periods are summarized as follows:

	For the Years Ended March 31,
	2018		2017		2016
	(dollars in thousands)
Operating Units Selling, G&A	$	62,529	$	57,004	$	56,110
Corporate G&A		41,205		33,940		37,193
	$	103,734	$	90,944	$	93,303

Earnings Per Share

	For the Years Ended March 31,
	2018			2017			2016
Weighted-Average Shares of Common Stock Outstanding		48,141,226			47,931,518			49,471,157
Effect of Dilutive Shares:
Assumed Exercise of Outstanding Dilutive Options		1,013,764			1,000,556			1,146,807
Less Shares Repurchased from Proceeds of Assumed Exercised Options		(727,904	)		(726,223	)		(768,886	)
Restricted Stock Units		218,900			155,435			221,751
Weighted-Average Common Stock and Dilutive Securities Outstanding		48,645,986			48,361,286			50,070,829

The line Less Shares Repurchased from Proceeds of Assumed Exercised Options includes unearned compensation related to outstanding stock options.

Share-Based Compensation

Fair Value Measures

Level 1 – Quoted prices for identical assets and liabilities in active markets;

Recent Accounting Pronouncements

RECENTLY ADOPTED

PENDING ADOPTION

Acquisition-Related Expense

Acquisition-related expense consists primarily of expenses incurred during the Fairborn Acquisition, as discussed in Footnote (B) to the Consolidated Financial Statements.

SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

Schedule of Inventories

Inventories consist of the following:

	March 31,
	2018		2017
	(dollars in thousands)
Raw Materials and Materials-in-Progress	$	121,628	$	122,736
Finished Cement		24,089		24,428
Aggregates		7,787		7,686
Gypsum Wallboard		8,477		7,951
Paperboard		8,602		8,635
Frac Sand		1,696		2,907
Repair Parts and Supplies		79,878		73,732
Fuel and Coal		6,002		4,771
	$	258,159	$	252,846

Schedule of Property, Plant and Equipment Estimated Lives

The estimated lives of the related assets are as follows:


Plants		20 to 30 years
Buildings		20 to 40 years
Machinery and Equipment		3 to 25 years

Schedule of Intangible Assets, Including Impact of Impairment Charge

Intangible Assets, including the impact of the impairment charges discussed above, at March 31, 2018 and 2017, consist of the following:

	March 31, 2018
	Amortization Period	Cost		Accumulated Amortization			Net
	(dollars in thousands)
Goodwill and Intangible Assets:
Customer Contracts and Relationships	15 years	$	72,260	$	(58,732	)	$	13,528
Sales Contracts	4 years		2,500		(2,500	)		—
Permits	40 years		28,640		(8,037	)		20,603
Goodwill			205,211		—			205,211
Total Goodwill and Intangible Assets		$	308,611	$	(69,269	)	$	239,342

	March 31, 2017
	Amortization Period	Cost		Accumulated Amortization			Net
	(dollars in thousands)
Goodwill and Intangible Assets:
Customer Contracts and Relationships	15 years	$	72,260	$	(56,303	)	$	15,957
Sales Contracts	4 years		2,500		(2,500	)	$	—
Permits	40 years		28,440		(7,262	)	$	21,178
Goodwill			198,370		—		$	198,370
Total Goodwill and Intangible Assets		$	301,570	$	(66,065	)	$	235,505

Schedule of Total Selling, General and Administrative Expenses

Total Selling, General, and Administrative expenses for each of the periods are summarized as follows:

	For the Years Ended March 31,
	2018		2017		2016
	(dollars in thousands)
Operating Units Selling, G&A	$	62,529	$	57,004	$	56,110
Corporate G&A		41,205		33,940		37,193
	$	103,734	$	90,944	$	93,303

Schedule of Earnings Per Share

	For the Years Ended March 31,
	2018			2017			2016
Weighted-Average Shares of Common Stock Outstanding		48,141,226			47,931,518			49,471,157
Effect of Dilutive Shares:
Assumed Exercise of Outstanding Dilutive Options		1,013,764			1,000,556			1,146,807
Less Shares Repurchased from Proceeds of Assumed Exercised Options		(727,904	)		(726,223	)		(768,886	)
Restricted Stock Units		218,900			155,435			221,751
Weighted-Average Common Stock and Dilutive Securities Outstanding		48,645,986			48,361,286			50,070,829

ACQUISITIONS (Tables)

12 Months Ended

Mar. 31, 2018

Business Combinations [Abstract]

Components of Purchase Price Allocation

The following table summarizes the allocation of the Fairborn Purchase Price to assets acquired and liabilities assumed as of the acquisition date:

Purchase Price Allocation at Acquisition Date

	As of February 10, 2017
	(dollars in thousands)
Inventories	$	11,106
Property and Equipment		314,897
Intangible Assets		10,000
Other Assets		2,820
Asset Retirement Obligation		(2,820	)
Total Net Assets		336,003
Goodwill		64,485
Total Estimated Purchase Price	$	400,488

Summary of Fair Value Estimates of Identifiable Intangible Assets and Weighted-Average Useful Lives

The following table is a summary of the fair value estimates of the identifiable intangible assets (dollars in thousands) and their weighted-average useful lives:

	Weighted Average Life		Estimated Fair Value
Customer Relationships		15		9,000
Permits		40		1,000
Total Intangible Assets			$	10,000

Net Sales and Operating Loss Related to Fairborn Acquisition

	For the Fiscal Year Ended March 31,
	2017
	(dollars in thousands)
Revenue	$	7,022
Operating Income (Loss)	$	(2,394	)

Unaudited Pro Forma Results

	For the Fiscal Year Ended March 31,
	2017		2016
	(dollars in thousands)
Revenue	$	1,280,511	$	1,218,254
Net Income	$	205,343	$	156,465
Earnings per share – basis	$	4.28	$	3.16
Earnings per share - diluted	$	4.25	$	3.12

PROPERTY, PLANT AND EQUIPMENT (Tables)

12 Months Ended

Mar. 31, 2018

Property Plant And Equipment [Abstract]

Schedule of Property, Plant and Equipment

Cost by major category and accumulated depreciation are summarized as follows:

	March 31,
	2018			2017
	(dollars in thousands)
Land and Quarries	$	423,543		$	402,698
Plants		1,871,213			1,820,908
Buildings, Machinery and Equipment		187,484			175,526
Construction in Progress		104,288			40,306
		2,586,528			2,439,438
Accumulated Depreciation		(991,229	)		(892,601	)
	$	1,595,299		$	1,546,837

ACCRUED EXPENSES (Tables)

12 Months Ended

Mar. 31, 2018

Payables And Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of the following:

	As of March 31,
	2018		2017
	(dollars in thousands)
Payroll and Incentive Compensation	$	25,290	$	22,850
Benefits		13,785		11,503
Interest		3,852		5,992
Property Taxes		5,422		4,759
Power and Fuel		1,545		1,536
Litigation Settlements		45,098		—
Legal		1,435		2,459
Sales and Use Tax		890		944
Acquisition Related Expenses		—		350
Other		8,553		4,986
	$	105,870	$	55,379

INDEBTEDNESS (Tables)

12 Months Ended

Mar. 31, 2018

Debt Instrument [Line Items]

Long-Term Debt

Long-term debt consists of the following:

	As of March 31,
	2018			2017
	(dollars in thousands)
Bank Credit Facility	$	240,000		$	225,000
4.500% Senior Unsecured Notes Due 2026		350,000			350,000
Private Placement Senior Unsecured Notes		36,500			117,714
Total Debt		626,500			692,714
Less: Current Portion of Long-term Debt		—			(81,214	)
Less: Debt Origination Costs		(5,578	)		(6,247	)
Long-term Debt	$	620,922		$	605,253

Schedule of Maturities of Long-Term Debt

Our maturities of long-term debt during the next five fiscal years and thereafter are as follows:

Fiscal Year	Amount
2019	$	—
2020		36,500
2021		—
2022		240,000
2023		—
Thereafter		350,000
Total	$	626,500

Schedule of Senior Unsecured Notes Redemption Prices

Beginning August 1, 2021, we may redeem some or all of the Senior Unsecured Notes at the redemption prices set forth below (expressed as a percentage of the principal amount being redeemed):

	Percentage
2021		102.25	%
2022		101.50	%
2023		100.75	%
2024 and thereafter		100.00	%

2007 Note Purchase Agreement [Member]

Debt Instrument [Line Items]

Amount Outstanding of Tranches

At March 31, 2018, the amounts outstanding for each of the remaining tranches are as follows:

		Principal		Maturity Date		Interest Rate
Tranche D		$36.5 million		October 2, 2019			6.48	%

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

12 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value of Senior Notes

	Fair Value
	(dollars in thousands)
Series 2007A Tranche D		37,849
4.500% Senior Unsecured Notes Due 2026		353,600

BUSINESS SEGMENTS (Tables)

12 Months Ended

Mar. 31, 2018

Segment Reporting [Abstract]

Financial Information Related to Operations by Segment

The table below sets forth certain financial information relating to our operations by segment.

	For the Years Ended March 31,
	2018			2017			2016
	(dollars in thousands)
Revenue -
Cement	$	651,750		$	566,321		$	528,499
Concrete and Aggregates		157,013			154,592			128,073
Gypsum Wallboard		491,779			473,651			461,457
Paperboard		181,742			167,065			149,192
Oil and Gas Proppants		85,496			34,623			57,591
Other		12,748			—			—
		1,580,528			1,396,252			1,324,812
Less: Intersegment Revenue		(88,124	)		(79,116	)		(73,862	)
Less: Joint Venture Revenue		(105,884	)		(105,916	)		(107,458	)
	$	1,386,520		$	1,211,220		$	1,143,492

	For the Years Ended March 31,
	2018		2017		2016
	(dollars in thousands)
Intersegment Revenue -
Cement	$	16,442	$	15,781	$	13,939
Concrete and Aggregates		1,335		1,262		922
Paperboard		70,347		62,073		59,001
	$	88,124	$	79,116	$	73,862
Cement Sales Volume (M tons) -
Wholly Owned		4,453		3,934		3,903
Joint Venture		912		937		875
		5,365		4,871		4,778

	For the Years Ended March 31,
	2018				2017			2016
				(dollars in thousands)
Operating Earnings -
Cement	$	179,151			$	153,525		$	137,854
Concrete and Aggregates		17,854				18,072			9,807
Gypsum Wallboard		158,551				159,866			159,352
Paperboard		32,758				37,601			32,153
Oil and Gas Proppants		(6,423	)			(14,633	)		(68,466	)
Other		284				—			—
Sub-Total		382,175				354,431			270,700
Corporate General and Administrative Expense		(41,205	)			(33,940	)		(37,193	)
Legal Settlements		(45,098	)			—			—
Other Non-Operating Income		3,728				2,139			2,328
Acquisition and Litigation Expense		—				(5,480	)		—
Earnings Before Interest and Income Taxes		299,600				317,150			235,835
Interest Expense, net		(27,638	)			(22,631	)		(16,583	)
Earnings Before Income Taxes	$	271,962			$	294,519		$	219,252
Cement Operating Earnings -
Wholly Owned	$	135,732			$	111,139		$	98,771
Joint Ventures		43,419				42,386			39,083
	$	179,151			$	153,525		$	137,854
Capital Expenditures -
Cement	$	45,088			$	32,790		$	20,262
Concrete and Aggregates		4,977				6,528			18,783
Gypsum Wallboard		19,382				11,393			4,832
Paperboard		5,177				3,996			5,542
Oil and Gas Proppants		56,872				1,534			40,144
Other, net		461				697			—
	$	131,957			$	56,938		$	89,563
Depreciation, Depletion and Amortization -
Cement	$	50,891			$	36,727		$	33,400
Concrete and Aggregates		7,931				7,931			6,260
Gypsum Wallboard		18,179				18,728			19,988
Paperboard		8,694				8,425			8,312
Oil and Gas Proppants		25,687				18,255			27,227
Corporate and Other		2,633				1,725			1,918
	$	114,015			$	91,791		$	97,105

	As of March 31,
	2018		2017		2016
	(dollars in thousands)
Identifiable Assets
Cement	$	1,247,504	$	1,234,617	$	819,994
Concrete and Aggregates		104,851		110,413		106,634
Gypsum Wallboard		386,041		379,414		392,523
Paperboard		123,819		124,356		127,371
Oil and Gas Proppants		401,421		376,306		409,497
Other, net		104,367		22,018		27,616
	$	2,368,003	$	2,247,124	$	1,883,635

Segment Breakdown of Goodwill

The segment breakdown of Goodwill at March 31, 2018 and 2017 is as follows:

	For the Years Ended March 31,
	2018		2017
	(dollars in thousands)
Cement	$	74,214	$	74,214
Gypsum Wallboard		116,618		116,618
Paperboard		7,538		7,538
Corporate and Other		6,841		—
	$	205,211	$	198,370

Summarized Financial Information for Joint Venture Unconsolidated

	For the Years Ended March 31,
	2018		2017
	(dollars in thousands)
Revenue	$	216,533	$	215,569
Gross Margin	$	91,647	$	90,098
Earnings Before Income Taxes	$	86,838	$	84,772

	March 31, 2018		March 31, 2017
	(dollars in thousands)
Current Assets	$	71,089	$	73,767
Non-Current Assets	$	66,856	$	42,337
Current Liabilities	$	20,671	$	22,293

INCOME TAXES (Tables)

12 Months Ended

Mar. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Components of Provision for Income Taxes

The provision for income taxes includes the following components:

	For the Years Ended March 31,
	2018			2017			2016
	(dollars in thousands)
Current Provision (Benefit) -
Federal	$	58,695		$	86,459		$	64,256
State		5,989			7,638			4,727
		64,684			94,097			68,983
Deferred Provision (Benefit) -
Federal		(52,333	)		7,274			(546	)
State		2,979			(5,071	)		(1,777	)
		(49,354	)		2,203			(2,323	)
Provision for Income Taxes	$	15,330		$	96,300		$	66,660

Schedule of Effective Tax Rates Vary from Federal Statutory Rates

The effective tax rates vary from the federal statutory rates due to the following items:

	For the Years Ended March 31,
	2018			2017			2016
	(dollars in thousands)
Earnings Before Income Taxes	$	271,962		$	294,519		$	219,252
Income Taxes at Statutory Rate	$	85,804		$	103,082		$	76,738
Increases (Decreases) in Tax Resulting from -
State Income Taxes, net		6,139			1,668			1,166
Statutory Depletion in Excess of Cost		(6,341	)		(1,216	)		(5,672	)
Domestic Production Activities Deduction		(5,995	)		(7,615	)		(6,302	)
Excess Tax Benefit from Stock Compensation		(4,129	)		—			—
Meals and Entertainment Disallowance		567			626			629
Limitation on Officer's Compensation		246			—			—
Impact of Tax Cuts and Jobs Act of 2017		(61,692	)		—			—
Other		731			(245	)		101
Provision for Income Taxes	$	15,330		$	96,300		$	66,660
Effective Tax Rate		6	%		33	%		30	%

Schedule of Components of Deferred Income Taxes

Components of deferred income taxes are as follows:

	March 31,
	2018			2017
	(dollars in thousands)
Items Giving Rise to Deferred Tax Liabilities -
Excess Tax Depreciation and Amortization	$	(106,367	)	$	(161,204	)
Depletion		(11,069	)		(18,638	)
State Income Taxes, net		(14,265	)		(11,455	)
Other		(5,957	)		(8,515	)
Total Deferred Tax Liabilities	$	(137,658	)	$	(199,812	)
Items Giving Rise to Deferred Tax Assets -
Change in Accruals	$	8,965		$	12,992
Inventory		4,276			1,242
Bad Debts		1,891			3,895
Long-term Incentive Compensation Plan		4,616			8,691
Credits and Other Carryforwards		12,879			13,103
Pension		1,108			4,178
Other		—			218
Subtotal		33,735			44,319
Valuation Allowance		(15,043	)		(10,531	)
Total Deferred Tax Assets	$	18,692		$	33,788

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Mar. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Minimum Annual Rental Commitments

Minimum annual rental commitments as of March 31, 2018, under noncancelable leases are set forth as follows (dollars in thousands):

Fiscal Year	Amount
2019	$	11,386
2020	$	8,235
2021	$	4,807
2022	$	3,359
2023	$	2,979
Thereafter	$	5,596

STOCK OPTION PLANS (Tables)

12 Months Ended

Mar. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Weighted-Average Assumptions Used to Value Option Awards

The weighted-average assumptions used in the Black-Scholes model to value the option awards in fiscal 2018 and 2017 are as follows:

	2018			2017
Dividend Yield		1.3	%		1.3	%
Expected Volatility		36.3	%		36.5	%
Risk Free Interest Rate		2.10	%		1.40	%
Expected Life	6.0 years			6.0 years

Stock Option Activity

The following table shows stock option activity for the years presented:

	For the Years Ended March 31,
	2018					2017					2016
	Number of Shares			Weighted Average Exercise Price		Number of Shares			Weighted Average Exercise Price		Number of Shares			Weighted Average Exercise Price
Outstanding Options at Beginning of Year		1,323,379		$	66.07		1,817,763		$	53.03		1,665,565		$	46.37
Granted		119,986		$	100.20		202,364		$	77.76		318,572		$	79.83
Exercised		(448,295	)	$	60.27		(677,566	)	$	34.46		(137,874	)	$	27.58
Cancelled		(36,934	)	$	79.97		(19,182	)	$	70.30		(28,500	)	$	86.35
Outstanding Options at End of Year		958,136		$	72.52		1,323,379		$	66.07		1,817,763		$	53.03
Options Exercisable at End of Year		651,218					874,116					1,285,412
Weighted Average Fair Value of Options Granted during the Year				$	33.37				$	25.22				$	24.27

Stock Options Outstanding

The following table summarizes information about stock options outstanding at March 31, 2018:

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number of Shares Outstanding		Weighted Average Remaining Contractual Life		Weighted Average Exercise Price		Number of Shares Outstanding		Weighted Average Exercise Price
$23.17 - $29.84		65,912		3.35	$	23.27		65,912	$	23.27
$33.43 - $37.34		99,582		4.21	$	33.94		99,582	$	33.94
$53.22 - $77.67		307,424		7.00	$	71.12		183,248	$	69.79
$79.73 - $106.00		485,218		7.37	$	88.02		302,476	$	84.72
		958,136		6.65	$	72.52		651,218	$	66.53

Summary of Activity for Nonvested Restricted Shares

The following table summarizes the activity for nonvested restricted shares during the fiscal year ended March 31, 2018:

	Number of Shares			Weighted Average Grant Date Fair Value
Restricted Stock Beginning of Year		371,213		$	60.33
Granted		107,964		$	100.05
Vested		(119,187	)	$	80.04
Forfeited		(31,931	)	$	40.00
Nonvested Restricted Stock at End of Year		328,059		$	65.76

NET INTEREST EXPENSE (Tables)

12 Months Ended

Mar. 31, 2018

Banking And Thrift Interest [Abstract]

Interest Expense, Net

The following components are included within Interest Expense, net:

	For the Years Ended March 31,
	2018			2017			2016
	(dollars in thousands)
Interest Income	$	(14	)	$	(40	)	$	(6	)
Interest Expense		26,433			21,595			15,891
Other Expenses		1,219			1,076			698
Interest Expense, net	$	27,638		$	22,631		$	16,583

PENSION AND PROFIT SHARING PLANS (Tables)

12 Months Ended

Mar. 31, 2018

Compensation And Retirement Disclosure [Abstract]

Schedule of Reconciliation of Obligations and Fair Values of Plan Assets

	For the Years Ended March 31,
	2018			2017
	(dollars in thousands)
Reconciliation of Benefit Obligations -
Benefit Obligation at April 1,	$	40,589		$	42,281
Service Cost - Benefits Earned During the Period		710			1,001
Interest Cost on Projected Benefit Obligation		1,466			1,584
Amendments		—			199
Actuarial (Gain) Loss		(4,505	)		(3,531	)
Settlement		(3,857	)		—
Benefits Paid		(1,033	)		(945	)
Benefit Obligation at March 31,	$	33,370		$	40,589
Reconciliation of Fair Value of Plan Assets -
Fair Value of Plan Assets at April 1,	$	26,410		$	21,424
Actual Return on Plan Assets		2,805			2,522
Employer Contributions		9,087			3,409
Settlement		(3,857	)		—
Benefits Paid		(1,033	)		(945	)
Fair Value of Plans at March 31,		33,412			26,410
Funded Status -
Funded (Unfunded) Status at March 31,	$	42		$	(14,179	)
Amounts Recognized in the Balance Sheet Consist of -
Prepaid and Other Assets	$	538		$	—
Accrued Benefit Liability		(496	)		(14,179	)
Accumulated Other Comprehensive Losses:
Net Actuarial Loss		5,198			11,587
Prior Service Cost		80			349
Accumulated Other Comprehensive Losses	$	5,278		$	11,936
Reclassification to Retained Earnings		978			—
Tax impact		(2,244	)		(4,540	)
Accumulated Other Comprehensive Losses, net of tax	$	4,012		$	7,396

Summary of Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets

The table below summarizes the Company’s Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets at March 31, 2018 and 2017:

	March 31,
	2018		2017
	(dollars in thousands)
Projected Benefit Obligation	$	33,370	$	40,589
Accumulated Benefit Obligation	$	33,367	$	40,391
Fair Value of Plan Assets	$	33,412	$	26,410

Components of Net Periodic Cost

Net periodic pension cost for the fiscal years ended March 31, 2018, 2017, and 2016, included the following components:

	For the Years Ended March 31,
	2018			2017			2016
	(dollar in thousands)
Service Cost - Benefits Earned During the Period	$	710		$	1,001		$	1,039
Interest Cost of Projected Benefit Obligation		1,466			1,584			1,525
Expected Return on Plan Assets		(2,137	)		(1,606	)		(1,751	)
Recognized Net Actuarial Loss		566			1,712			1,773
Amortization of Prior-Service Cost		269			359			300
Settlement		649			—			—
Net Periodic Pension Cost	$	1,523		$	3,050		$	2,886

Schedule of Expected Benefit Payments

Expected benefit payments over the next five years, and the following five years under the pension plans are expected to be as follows (dollars in thousands):

Fiscal Years	Total
2019	$	1,350
2020	$	1,416
2021	$	1,520
2022	$	1,604
2023	$	1,657
2024-2028	$	9,412

Schedule of Assumptions Used in Net Periodic Benefit Cost and Benefit Obligations

The following tables set forth the assumptions used in the actuarial calculations of the present value of Net Periodic Benefit Costs and Benefit Obligations:

	March 31,
	2018			2017			2016
Net Periodic Benefit Costs -
Discount Rate		4.03	%		3.83	%		3.70	%
Expected Return on Plan Assets		7.50	%		7.50	%		8.00	%
Rate of Compensation Increase		3.50	%		3.50	%		3.50	%

	March 31,
	2018			2017
Benefit Obligations -
Discount Rate		4.12	%		4.03	%
Rate of Compensation Increase		3.50	%		3.50	%

Schedule of Pension Plans Weighted-Average Asset Allocation and Range of Target Allocation

The pension plans’ approximate weighted-average asset allocation at March 31, 2018 and 2017 and the range of target allocation are as follows:

		Percentage of Plan Assets at March 31,
	Range of Target Allocation	2018			2017
Asset Category -
Equity Securities	40 – 60%		50	%		70	%
Debt Securities	35 – 60%		47	%		27	%
Other	0 – 5%		3	%		3	%
Total			100	%		100	%

Schedule of Fair Values of Defined Benefit Plans

The fair values of our defined benefit plans’ consolidated assets by category as of March 31, 2018 and 2017 were as follows:

	March 31,
	2018		2017
	(dollars in thousands)
Equity Securities	$	16,533	$	18,375
Fixed Income Securities		15,799		7,166
Real Estate Funds		163		147
Commodity Linked Funds		213		464
Cash Equivalents		704		258
Total	$	33,412	$	26,410

Schedule of Fair Values of Defined Benefit Plans Determined Using Fair Value Hierarchy of Inputs

The fair values by category of inputs as of March 31, 2018 were as follows:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Asset Categories	(dollars in thousands)
Equity Securities	$	—	$	16,533	$	—	$	16,533
Fixed Income Securities		—		15,799		—		15,799
Real Estate Funds		—		163		—		163
Commodity Linked Funds		—		213		—		213
Cash Equivalents		704		—		—		704
	$	704	$	32,708	$	—	$	33,412

The fair values by category of inputs as of March 31, 2017 were as follows:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Asset Categories	(dollars in thousands)
Equity Securities	$	—	$	18,375	$	—	$	18,375
Fixed Income Securities		—		7,166		—		7,166
Real Estate Funds		—		147		—		147
Commodity Linked Funds		—		464		—		464
Cash Equivalents		258		—		—		258
	$	258	$	26,152	$	—	$	26,410

FINANCIAL STATEMENTS FOR GUARANTORS OF THE 4.500% SENIOR UNSECURED NOTES (Tables)

12 Months Ended

Mar. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Condensed Consolidating Statement of Earnings and Comprehensive Earnings

Condensed Consolidating Statement of Earnings and Comprehensive Earnings For the Year Ended March 31, 2018	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
Revenue	$	—		$	1,386,520		$	—		$	1,386,520
Cost of Goods Sold		—			1,047,764			—			1,047,764
Gross Profit		—			338,756			—			338,756
Equity in Earnings of Unconsolidated Joint Venture		43,419			43,419			(43,419	)		43,419
Equity in Earnings of Subsidiaries		289,950			—			(289,950	)		—
Corporate General and Administrative Expenses		(37,825	)		(3,380	)		—			(41,205	)
Legal Settlements		(45,098	)		—			—			(45,098	)
Other Non-Operating Income		(233	)		3,961			—			3,728
Interest Expense, net		(27,609	)		(29	)		—			(27,638	)
Earnings before Income Taxes		222,604			382,727			(333,369	)		271,962
Income Taxes		34,028			(49,358	)		—			(15,330	)
Net Earnings	$	256,632		$	333,369		$	(333,369	)	$	256,632
Net Earnings	$	256,632		$	333,369		$	(333,369	)	$	256,632
Net Actuarial Change in Benefit Plans, net of tax		3,384			3,384			(3,384	)		3,384
Comprehensive Earnings	$	260,016		$	336,753		$	(336,753	)	$	260,016

Condensed Consolidating Statement of Earnings and Comprehensive Earnings For the Year Ended March 31, 2017	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
Revenue	$	—		$	1,211,220		$	—		$	1,211,220
Cost of Goods Sold		—			899,175			—			899,175
Gross Profit		—			312,045			—			312,045
Equity in Earnings of Unconsolidated Joint Venture		42,386			42,386			(42,386	)		42,386
Equity in Earnings of Subsidiaries		210,923			—			(210,923	)		—
Corporate General and Administrative Expenses		(28,545	)		(5,395	)		—			(33,940	)
Other Non-Operating Income		(534	)		2,673			—			2,139
Acquisition-Related Expense		(5,480	)		0			—			(5,480	)
Interest Expense, net		(51,315	)		28,684			—			(22,631	)
Earnings before Income Taxes		167,435			380,393			(253,309	)		294,519
Income Taxes		30,784			(127,084	)		—			(96,300	)
Net Earnings	$	198,219		$	253,309		$	(253,309	)	$	198,219
Net Earnings	$	198,219		$	253,309		$	(253,309	)		198,219
Net Actuarial Change in Benefit Plans, net of tax		4,013			4,013			(4,013	)		4,013
Comprehensive Earnings	$	202,232		$	257,322		$	(257,322	)	$	202,232

Condensed Consolidating Statement of Earnings and Comprehensive Earnings For the Year Ended March 31, 2016	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
Revenue	$	—		$	1,143,492		$	—		$	1,143,492
Cost of Goods Sold		—			911,875			—			911,875
Gross Profit		—			231,617			—			231,617
Equity in Earnings of Unconsolidated Joint Venture		39,083			39,083			(39,083	)		39,083
Equity in Earnings of Subsidiaries		160,018			—			(160,018	)		—
Corporate General and Administrative Expenses		(32,047	)		(5,146	)		—			(37,193	)
Other Non-Operating Income		(398	)		2,726			—			2,328
Interest Expense, net		(39,038	)		22,455			—			(16,583	)
Earnings before Income Taxes		127,618			290,735			(199,101	)		219,252
Income Taxes		24,974			(91,634	)		—			(66,660	)
Net Earnings	$	152,592		$	199,101		$	(199,101	)	$	152,592
Net Earnings	$	152,592		$	199,101		$	(199,101	)	$	152,592
Net Actuarial Change in Benefit Plans, net of tax		658			658			(658	)		658
Comprehensive Earnings	$	153,250		$	199,759		$	(199,759	)	$	153,250

Condensed Consolidating Balance Sheet

Condensed Consolidating Balance Sheet At March 31, 2018	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
ASSETS
Current Assets -
Cash and Cash Equivalents	$	5,784		$	3,531		$	—		$	9,315
Restricted Cash		38,753			—						38,753
Accounts and Notes Receivable		407			141,278			—			141,685
Inventories		—			258,159			—			258,159
Income Tax Receivable		109,510			—			(103,760	)		5,750
Prepaid and Other Current Assets		665			4,408			—			5,073
Total Current Assets		155,119			407,376			(103,760	)		458,735
Property, Plant, and Equipment -		3,188			2,583,340			—			2,586,528
Less: Accumulated Depreciation		(1,089	)		(990,140	)		—			(991,229	)
Property, Plant and Equipment, net		2,099			1,593,200			-			1,595,299
Notes Receivable		—			115			—			115
Investment in Joint Venture		70			60,488			—			60,558
Investments in Subsidiaries and Receivables from Affiliates		2,718,809			762,340			(3,481,149	)		—
Goodwill and Intangible Assets, net		—			239,342			—			239,342
Other Assets		5,417			8,537			—			13,954
	$	2,881,514		$	3,071,398		$	(3,584,909	)	$	2,368,003
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities-
Accounts Payable	$	5,591		$	67,868		$	—		$	73,459
Accrued Liabilities		67,387			38,483			—			105,870
Income Tax Payable		—			103,760			(103,760	)		—
Current Portion of Long-term Debt		—			—			—			—
Total Current Liabilities		72,978			210,111			(103,760	)		179,329
Long-term Debt		620,922			—			—			620,922
Other Long-term Liabilities		124			30,972			—			31,096
Payables to Affiliates		762,340			5,608,236			(6,370,576	)		—
Deferred Income Taxes		7,460			111,506			—			118,966
Total Liabilities		1,463,824			5,960,825			(6,474,336	)		950,313
Total Stockholders’ Equity		1,417,690			(2,889,427	)		2,889,427			1,417,690
	$	2,881,514		$	3,071,398		$	(3,584,909	)	$	2,368,003

Condensed Consolidating Balance Sheet At March 31, 2017	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
ASSETS
Current Assets -
Cash and Cash Equivalents	$	5,184		$	1,377		$	—		$	6,561
Accounts and Notes Receivable		422			135,891			—			136,313
Inventories		—			252,846			—			252,846
Income Tax Receivable		33,196			—			(33,196	)		—
Prepaid and Other Current Assets		484			4,420			—			4,904
Total Current Assets		39,286			394,534			(33,196	)		400,624
Property, Plant, and Equipment -		2,914			2,436,524			—			2,439,438
Less: Accumulated Depreciation		(937	)		(891,664	)		—			(892,601	)
Property, Plant and Equipment, net		1,977			1,544,860			—			1,546,837
Notes Receivable		—			815			—			815
Investment in Joint Venture		51			48,569			—			48,620
Investments in Subsidiaries and Receivables from Affiliates		5,126,289			3,252,309			(8,378,598	)		—
Goodwill and Intangible Assets, net		—			235,505			—			235,505
Other Assets		5,687			9,036			—			14,723
	$	5,173,290		$	5,485,628		$	(8,411,794	)	$	2,247,124
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities-
Accounts Payable	$	6,687		$	85,506		$	—		$	92,193
Accrued Liabilities		21,043			34,336			—			55,379
Income Tax Payable		733			33,196			(33,196	)		733
Current Portion of Long-term Debt		81,214			—			—			81,214
Total Current Liabilities		109,677			153,038			(33,196	)		229,519
Long-term Debt		605,253			—			—			605,253
Other Long-term Liabilities		189			42,689			—			42,878
Payables to Affiliates		3,252,309			2,825,710			(6,078,019	)		—
Deferred Income Taxes		2,412			163,612			—			166,024
Total Liabilities		3,969,840			3,185,049			(6,111,215	)		1,043,674
Total Stockholders’ Equity		1,203,450			2,300,579			(2,300,579	)		1,203,450
	$	5,173,290		$	5,485,628		$	(8,411,794	)	$	2,247,124

Condensed Consolidating Statement of Cash Flows

Condensed Consolidating Statement of Cash Flows For the Year Ended March 31, 2018	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	$	(83,947	)	$	421,612		$	—		$	337,665
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment		(142	)		(131,815	)		—			(131,957	)
Investment in Subsidiaries		(36,761	)		—			36,761			—
Acquisition Spending		—			(36,761	)		—			(36,761	)
Net Cash Used in Investing Activities		(36,903	)		(168,576	)		36,761			(168,718	)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase in Credit Facility		15,000			—			—			15,000
Repayment of Senior Notes		(81,214	)		—			—			(81,214	)
Dividends Paid to Stockholders		(19,438	)		—			—			(19,438	)
Purchase and Retirement of Common Stock		(61,078	)		—			—			(61,078	)
Proceeds from Stock Option Exercises		24,264			—			—			24,264
Shares Redeemed to Settle Employee Taxes on Stock Compensation		(4,974	)		—			—			(4,974	)
Intra-entity Activity, net		287,643			(250,882	)		(36,761	)		—
Net Cash Provided by (Used in) Financing Activities		160,203			(250,882	)		(36,761	)		(127,440	)
NET INCREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH		39,353			2,154			—			41,507
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD		5,184			1,377			—			6,561
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	$	44,537		$	3,531		$	—		$	48,068

Condensed Consolidating Statement of Cash Flows For the Year Ended March 31, 2017	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	$	(64,376	)	$	395,974		$	—		$	331,598
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment		(697	)		(56,241	)		—			(56,938	)
Investment in Subsidiaries		(400,488	)		—			400,488			—
Acquisition Spending		—			(400,488	)		—			(400,488	)
Net Cash Used in Investing Activities		(401,185	)		(456,729	)		400,488			(457,426	)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase in Credit Facility		(157,000	)		—			—			(157,000	)
Repayment of Senior Notes		(8,000	)		—			—			(8,000	)
Issuance of Long-term Debt		350,000			—			—			350,000
Payment of Debt Issuance Costs		(6,637	)		—			—			(6,637	)
Dividends Paid to Stockholders		(19,341	)		—			—			(19,341	)
Purchase and Retirement of Common Stock		(60,013	)		—			—			(60,013	)
Proceeds from Stock Option Exercises		22,108			—			—			22,108
Shares Redeemed to Settle Employee Taxes on Stock Compensation		(4,468	)		—			—			(4,468	)
Excess Tax Benefits from Share Based Payment Arrangements		10,349			—			—			10,349
Intra-entity Activity, net		340,240			60,248			(400,488	)		—
Net Cash Provided by (Used in) Financing Activities		467,238			60,248			(400,488	)		126,998
NET INCREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH		1,677			(507	)		—			1,170
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD		3,507			1,884			—			5,391
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	$	5,184		$	1,377		$	—		$	6,561

Condensed Consolidating Statement of Cash Flows For the Year Ended March 31, 2016	Parent			Guarantor Subsidiaries			Eliminations			Consolidated
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	$	(37,985	)	$	303,752		$	—		$	265,767
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment		—			(89,563	)		—			(89,563	)
Investment in Subsidiaries		(32,427	)		—			32,427			—
Acquisition Spending		—			(32,427	)		—			(32,427	)
Net Cash Used in Investing Activities		(32,427	)		(121,990	)		32,427			(121,990	)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase in Credit Facility		52,000			—			—			52,000
Repayment of Senior Notes		(57,045	)		—			—			(57,045	)
Dividends Paid to Stockholders		(20,020	)		—			—			(20,020	)
Purchase and Retirement of Common Stock		(123,530	)		—			—			(123,530	)
Proceeds from Stock Option Exercises		2,866			—			—			2,866
Shares Redeemed to Settle Employee Taxes on Stock Compensation		(4,273	)		—			—			(4,273	)
Excess Tax Benefits from Share Based Payment Arrangements		4,102			—			—			4,102
Intra-entity Activity, net		216,175			(183,748	)		(32,427	)		—
Net Cash Provided by (Used in) Financing Activities		70,275			(183,748	)		(32,427	)		(145,900	)
NET INCREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH		(137	)		(1,986	)		—			(2,123	)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD		3,644			3,870			—			7,514
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	$	3,507		$	1,884		$	—		$	5,391

QUARTERLY RESULTS (UNAUDITED) (Tables)

12 Months Ended

Mar. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Results (unaudited)

	For the Years Ended March 31,
	2018		2017
	(dollars in thousands, except per share data)
First Quarter -
Revenue	$	366,121	$	297,504
Gross Profit		86,059		71,955
Earnings Before Income Taxes		79,530		67,276
Net Earnings		54,882		45,344
Diluted Earnings Per Share	$	1.13	$	0.93
Second Quarter -
Revenue	$	376,315	$	332,658
Gross Profit		96,754		91,210
Earnings Before Income Taxes		92,319		89,373
Net Earnings		63,362		60,237
Diluted Earnings Per Share	$	1.31	$	1.25
Third Quarter -
Revenue	$	359,371	$	302,395
Gross Profit		94,566		87,380
Earnings Before Income Taxes		51,388		83,689
Net Earnings		101,380		56,387
Diluted Earnings Per Share	$	2.08	$	1.17
Fourth Quarter -
Revenue	$	284,713	$	278,663
Gross Profit		61,377		61,500
Earnings Before Income Taxes		48,725		54,181
Net Earnings		37,008		36,251
Diluted Earnings Per Share	$	0.76	$	0.75

Significant Accounting Policies - Additional Information (Detail)	2 Months Ended	3 Months Ended		12 Months Ended
	May 21, 2018 $ / shares shares	Mar. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)	Mar. 31, 2018 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) Customer $ / shares shares	Mar. 31, 2016 USD ($) $ / shares shares	Aug. 10, 2015 shares
Significant Accounting Policies [Line Items]
Allowance for doubtful accounts				$ 8,600,000	$ 10,700,000
Bad debt expense				800,000
Uncollectible accounts, wrote-off				2,900,000
Notes receivable, total				2,300,000
Notes receivable, current				$ 2,200,000
Notes receivable interest rate				3.50%
Notes Receivable basis spread on Prime rate				5.10%
Notes receivable, maturity description				Remaining unpaid amounts, plus accrued interest, mature in fiscal 2019 and 2021.
Inventories wrote down					8,492,000	$ 9,382,000
Depreciable assets				$ 109,600,000	86,000,000	84,200,000
Basis of valuation				Property, plant, and equipment are stated at cost.
Depreciation method				straight-line basis over the estimated useful lives
Impairment of Intangible Assets		$ 6,600,000	$ 28,400,000			34,999,000
Impairment of long-lived and intangible assets				$ 0	0
Reduction of prepaid sand liability					2,000,000	10,658,000
Intangible Assets, Amortization Expense				4,400,000	$ 4,800,000	$ 12,900,000
Amortization expense, expected, for fiscal year 2019				3,200,000
Amortization expense, expected, for fiscal year 2020				2,200,000
Amortization expense, expected, for fiscal year 2021				1,700,000
Amortization expense, expected, for fiscal year 2022				1,700,000
Amortization expense, expected, for fiscal year 2023				$ 1,700,000
Number of additional shares authorized to be repurchased \| shares							6,782,700
Outstanding authorization shares \| shares							7,500,000
Repurchase of shares \| shares				627,772	788,800	1,894,000
Shares repurchased average price \| $ / shares				$ 97.30	$ 76.08	$ 65.24
Freight costs included in revenue and cost of goods sold				$ 158,300,000	$ 138,000,000	$ 139,500,000
Accumulated other comprehensive loss				4,012,000	7,396,000
Net of income taxes for accumulated other comprehensive loss				1,300,000
Interest payments				28,900,000	19,000,000	16,900,000
Net payments made for federal and state income taxes				69,400,000	76,100,000	63,900,000
Maintenance and repair expenses				$ 107,300,000	$ 101,500,000	$ 95,100,000
Stock options excluded from computation of diluted earnings per share \| shares				98,362	513,262	688,420
Stock options, average exercise price per share \| $ / shares				$ 98.75	$ 80.59	$ 80.51
Increase in gross profit				$ 800,000
Decrease in other income				(800,000)
ASU 2016-09 [Member]
Significant Accounting Policies [Line Items]
Cumulative effect reduction in retained earnings				700,000
Impact to retained earnings				0
Recognition of excess tax benefits in provision for income taxes				4,100,000
ASU 2018-02 [Member]
Significant Accounting Policies [Line Items]
Reclassification of income tax effect from accumulated other comprehensive loss to retained earnings				$ 1,000,000
Subsequent Event [Member]
Significant Accounting Policies [Line Items]
Repurchase of shares \| shares	319,300
Shares repurchased average price \| $ / shares	$ 101.39
Stock repurchase remaining number of shares authorized to be repurchased \| shares	3,870,128
Sand [Member]
Significant Accounting Policies [Line Items]
Customer advances		$ 2,000,000				$ 2,000,000
Date of contract termination				Jun. 30, 2016
Customer Contracts And Relationships [Member]
Significant Accounting Policies [Line Items]
Intangible Assets, Net				$ 13,528,000	$ 15,957,000
Oil and Gas Proppants [Member]
Significant Accounting Policies [Line Items]
Reduction of prepaid sand liability				2,000,000
Number of customers terminated contract \| Customer					2
Settlement agreements, amount received					$ 12,900,000
Oil and Gas Proppants [Member] \| Customer Contracts And Relationships [Member]
Significant Accounting Policies [Line Items]
Intangible Assets, Net				$ 1,600,000
Intangible assets, wrote-off due to termination of contract					1,300,000
Oil and Gas Proppants [Member] \| Raw Materials [Member]
Significant Accounting Policies [Line Items]
Inventories wrote down					7,700,000
Oil and Gas Proppants [Member] \| Materials-in-Process and Frac Sand [Member]
Significant Accounting Policies [Line Items]
Inventories wrote down					$ 800,000

Schedule of Inventories (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Inventory [Line Items]
Inventories	$ 258,159	$ 252,846
Raw Materials and Material-in-Progress [Member]
Inventory [Line Items]
Inventories	121,628	122,736
Finished Cement [Member]
Inventory [Line Items]
Inventories	24,089	24,428
Aggregates [Member]
Inventory [Line Items]
Inventories	7,787	7,686
Gypsum Wallboard [Member]
Inventory [Line Items]
Inventories	8,477	7,951
Paperboard [Member]
Inventory [Line Items]
Inventories	8,602	8,635
Frac Sand [Member]
Inventory [Line Items]
Inventories	1,696	2,907
Repair Parts and Supplies [Member]
Inventory [Line Items]
Inventories	79,878	73,732
Fuel and Coal [Member]
Inventory [Line Items]
Inventories	$ 6,002	$ 4,771

Schedule of Property, Plant And Equipment Estimated Lives (Detail)	12 Months Ended
	Mar. 31, 2018
Minimum [Member] \| Plants [Member]
Property, Plant and Equipment [Line Items]
Estimated lives of assets - (years)	20 years
Minimum [Member] \| Buildings [Member]
Property, Plant and Equipment [Line Items]
Estimated lives of assets - (years)	20 years
Minimum [Member] \| Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated lives of assets - (years)	3 years
Maximum [Member] \| Plants [Member]
Property, Plant and Equipment [Line Items]
Estimated lives of assets - (years)	30 years
Maximum [Member] \| Buildings [Member]
Property, Plant and Equipment [Line Items]
Estimated lives of assets - (years)	40 years
Maximum [Member] \| Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated lives of assets - (years)	25 years

Schedule of Intangible Assets, Including Impact of Impairment Charges (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Accumulated Amortization	$ (69,269)	$ (66,065)
Goodwill, Cost	205,211	198,370
Goodwill, Net	205,211	198,370
Total Goodwill and Intangible Assets, Cost	308,611	301,570
Total Goodwill and Intangible Assets, Net	$ 239,342	$ 235,505
Customer Contracts And Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life	15 years	15 years
Intangible Assets, Cost	$ 72,260	$ 72,260
Intangible Assets, Accumulated Amortization	(58,732)	(56,303)
Intangible Assets, Net	$ 13,528	$ 15,957
Sales Contracts [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life	4 years	4 years
Intangible Assets, Cost	$ 2,500	$ 2,500
Intangible Assets, Accumulated Amortization	$ (2,500)	$ (2,500)
Permits [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life	40 years	40 years
Intangible Assets, Cost	$ 28,640	$ 28,440
Intangible Assets, Accumulated Amortization	(8,037)	(7,262)
Intangible Assets, Net	$ 20,603	$ 21,178

Schedule of Total Selling, General and Administrative Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Accounting Policies [Abstract]
Operating Units Selling, G&A	$ 62,529	$ 57,004	$ 56,110
Corporate G&A	41,205	33,940	37,193
Total selling, general and administrative expenses	$ 103,734	$ 90,944	$ 93,303

Schedule of Earnings Per Share (Detail) - shares	12 Months Ended
Schedule of Earnings Per Share (Detail) - shares	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Weighted-Average Shares of Common Stock Outstanding	48,141,226	47,931,518	49,471,157
Assumed Exercise of Outstanding Dilutive Options	1,013,764	1,000,556	1,146,807
Less Shares Repurchased from Proceeds of Assumed Exercised Options	(727,904)	(726,223)	(768,886)
Restricted Stock Units	218,900	155,435	221,751
Weighted-Average Common Stock and Dilutive Securities Outstanding	48,645,986	48,361,286	50,070,829

Acquisitions - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Jul. 27, 2017	Feb. 10, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Business Acquisition [Line Items]
Operating income (loss)			$ 382,175	$ 354,431	$ 270,700
Purchase price paid for business acquisition			36,761	400,488	32,427
Goodwill			$ 205,211	198,370
Fairborn Acquisition [Member]
Business Acquisition [Line Items]
Business acquisition, date of acquisition			Feb. 10, 2017
Business acquisition purchase price		$ 400,500
Other assets		2,820
Asset retirement obligation		2,820
Provisional other assets recorded previously		4,000
Provisional asset retirement obligation recorded previously		4,000
Depreciation and amortization			$ 14,600	1,900
Operating income (loss)				(2,394)
Material nonrecurring charges					$ 5,500
Property and equipment		314,897
Goodwill		$ 64,485
Fairborn Acquisition [Member] \| Fair Value Adjustment To Inventory [Member]
Business Acquisition [Line Items]
Operating income (loss)			$ 500	$ 1,500
Wildcat Minerals LLC [Member]
Business Acquisition [Line Items]
Business acquisition, effective date of acquisition			Jul. 27, 2017
Purchase price paid for business acquisition	$ 36,800
Current assets	3,100
Property and equipment	28,300
Intangible and other assets	1,400
Current liabilities	2,800
Goodwill	$ 6,800

Components of Purchase Price Allocation (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Feb. 10, 2017
Business Acquisition [Line Items]
Intangible Assets	$ 10,000
Goodwill	$ 205,211	$ 198,370
Fairborn Acquisition [Member]
Business Acquisition [Line Items]
Inventories			$ 11,106
Property and Equipment			314,897
Intangible Assets			10,000
Other Assets			2,820
Asset Retirement Obligation			(2,820)
Total Net Assets			336,003
Goodwill			64,485
Total Estimated Purchase Price			$ 400,488

Summary of Fair Value Estimates of Identifiable Intangible Assets and Weighted-Average Useful Lives (Detail) $ in Thousands	12 Months Ended
	Mar. 31, 2018 USD ($)
Acquired Finite Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 10,000
Customer Relationships [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Weighted Average Life	15 years
Estimated Fair Value	$ 9,000
Permits [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Weighted Average Life	40 years
Estimated Fair Value	$ 1,000

Net Sales and Operating Loss Related to Fairborn Acquisition (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Business Acquisition Pro Forma Information Nonrecurring Adjustment [Line Items]
Revenue	$ 284,713	$ 359,371	$ 376,315	$ 366,121	$ 278,663	$ 302,395	$ 332,658	$ 297,504	$ 1,386,520	$ 1,211,220	$ 1,143,492
Operating Income (Loss)									$ 382,175	354,431	$ 270,700
Fairborn Acquisition [Member]
Business Acquisition Pro Forma Information Nonrecurring Adjustment [Line Items]
Revenue										7,022
Operating Income (Loss)										$ (2,394)

Unaudited Pro Forma Results (Detail) - Fairborn Acquisition [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Business Acquisition [Line Items]
Revenue	$ 1,280,511	$ 1,218,254
Net Income	$ 205,343	$ 156,465
Earnings per share – basis	$ 4.28	$ 3.16
Earnings per share - diluted	$ 4.25	$ 3.12

Schedule of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,586,528	$ 2,439,438
Accumulated Depreciation	(991,229)	(892,601)
Property, Plant, and Equipment, net	1,595,299	1,546,837
Land And Quarries [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	423,543	402,698
Plants [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,871,213	1,820,908
Buildings Machinery And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	187,484	175,526
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 104,288	$ 40,306

Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Accounts Payable And Accrued Liabilities Current [Abstract]
Payroll and Incentive Compensation	$ 25,290	$ 22,850
Benefits	13,785	11,503
Interest	3,852	5,992
Property Taxes	5,422	4,759
Power and Fuel	1,545	1,536
Litigation Settlements	45,098
Legal	1,435	2,459
Sales and Use Tax	890	944
Acquisition Related Expenses		350
Other	8,553	4,986
Accrued expenses, total	$ 105,870	$ 55,379

Long-Term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Debt Instrument [Line Items]
Bank Credit Facility	$ 240,000	$ 225,000
Total Debt	626,500	692,714
Less: Current Portion of Long-term Debt		(81,214)
Less: Debt Origination Costs	(5,578)	(6,247)
Long-term Debt	620,922	605,253
4.500% Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Total Debt	350,000	350,000
Private Placement Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Total Debt	$ 36,500	$ 117,714

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References + Details

Long-Term Debt (Parenthetical) (Detail) - 4.500% Senior Unsecured Notes Due 2026 [Member]	12 Months Ended
	Mar. 31, 2018	Aug. 02, 2016
Debt Instrument [Line Items]
Debt instrument, interest rate	4.50%	4.50%
Debt instrument, maturity year	2026

Indebtedness - Additional Information (Detail)			12 Months Ended
Indebtedness - Additional Information (Detail)	Aug. 02, 2016 USD ($)	Oct. 31, 2014	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016	Oct. 02, 2007 USD ($) Loan
Debt Instrument [Line Items]
Interest coverage ratio		250.00%
Unused line of credit commitment fee based on leverage ratio		0.10%
Borrowings outstanding under Credit Facility			$ 240,000,000	$ 225,000,000
Bank Credit Facility, borrowings available			252,500,000
Letter of Credit Facility			40,000,000
Letters of credit outstanding, amount			$ 7,500,000
Maximum [Member]
Debt Instrument [Line Items]
Consolidated funded indebtedness ratio		350.00%
Unused line of credit commitment fee based on leverage ratio		0.35%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Variable margin		1.00%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Variable margin		2.25%
Federal Funds Effective Swap Rate [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Variable margin		0.00%
Federal Funds Effective Swap Rate [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Variable margin		1.25%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Weighted-average interest rate			2.60%	1.90%	1.60%
Interest rate of debt instrument			3.20%	2.40%
Credit Facility, principal balance			$ 500,000,000
Credit Facility, termination date			Aug. 02, 2021
Credit Facility, interest rate description			At our option, outstanding principal amounts on the Credit Facility bear interest at a variable rate equal to (i) LIBOR, plus an agreed margin (ranging from 100 to 225 basis points), which is to be established quarterly based upon the Company’s ratio of consolidated EBITDA, defined as earnings before interest, taxes, depreciation and amortization, to the Company’s consolidated indebtedness (the Leverage Ratio), or (ii) an alternative base rate which is the higher of (a) the prime rate or (b) the federal funds rate plus 1/2% per annum plus an agreed margin (ranging from 0 to 125 basis points). Interest payments are payable, in the case of loans bearing interest at a rate based on the federal funds rate, quarterly, or in the case of loans bearing interest at a rate based on LIBOR, at the end of the LIBOR advance periods, which can be a period of up to nine months at the option of the Company. The Company is also required to pay a commitment fee on unused available borrowings under the Credit Facility ranging from 10 to 35 basis points depending upon the Leverage Ratio. The Credit Facility contains customary covenants that restrict our ability to incur additional debt; encumber our assets; sell assets; make or enter into certain investments, loans or guaranties, and enter into sale and leaseback arrangements. The Credit Facility also requires us to maintain a consolidated indebtedness ratio (calculated as consolidated indebtedness to consolidated earnings before interest, taxes, depreciation, amortization, certain transaction-related deductions and other non-cash deductions) of 3.5:1.0 or less and an interest coverage ratio (consolidated earnings before interest, taxes, depreciation, amortization, certain transaction-related deductions and other non-cash deductions to consolidated interest expense) of at least 2.5:1.0. We had $240.0 million of borrowings outstanding at March 31, 2018. Based on our Leverage Ratio, we had $252.5 million of available borrowings, net of the outstanding letters of credit, at March 31, 2018.
Line of Credit \| Federal Funds Effective Swap Rate [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Variable margin		0.50%
Letter of Credit [Member]
Debt Instrument [Line Items]
Bank Credit Facility, one-time fee			0.125%
Private Placement Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Weighted-average interest rate			6.00%	6.00%	5.90%
Interest rate of debt instrument			6.50%	6.00%
Swingline Loan [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit Facility, principal balance			$ 25,000,000
4.500% Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 350,000,000
Debt instrument, interest rate	4.50%		4.50%
Debt instrument, maturity period	2026-08
4.500% Senior Unsecured Notes Due 2026 [Member] \| Prior to August 1, 2019 [Member]
Debt Instrument [Line Items]
Redemption price, percentage	104.50%
4.500% Senior Unsecured Notes Due 2026 [Member] \| On or After August 1, 2019 and Prior to August 1, 2021 [Member]
Debt Instrument [Line Items]
Redemption price, percentage	100.00%
4.500% Senior Unsecured Notes Due 2026 [Member] \| Maximum [Member] \| Prior to August 1, 2019 [Member]
Debt Instrument [Line Items]
Percentage of principal amount redeemable	40.00%
2007 Note Purchase Agreement [Member]
Debt Instrument [Line Items]
Interest coverage ratio			250.00%
Senior Notes, sale						$ 200,000,000
Number of tranches \| Loan						4
Senior Notes, payment terms			Interest for the Series 2007A Senior Unsecured Notes is payable semi-annually on April 2 and October 2 of each year until all principal is paid for the respective tranche.
Purchase agreement additional requirements			and to maintain an interest coverage ratio (Consolidated EBITDA to Consolidated Interest Expense [calculated as Consolidated EBITDA, defined above, to consolidated interest expense]) of at least 2.50 to 1.0. In addition, the 2007 Note Purchase Agreement requires the Company to ensure that at all times either (i) Consolidated Total Assets equal at least 80% of the consolidated total assets of the Company and its Subsidiaries, determined in accordance with GAAP, or (ii) Consolidated Total Revenue of the Company and its Restricted Subsidiaries for the period of four consecutive fiscal quarters most recently ended equals at least 80% of the consolidated total revenue of the Company and its Subsidiaries during such period.
Senior Notes, permitted minimum aggregate principal amount prepayment without penalty			10.00%
Percentage of face value to be paid if notes are prepaid			100.00%
Senior Notes, calculation of make-whole amount, description			Discounting the remaining scheduled principal and interest payments at a discount rate of 50 basis
Discount on Senior Notes principal and interest			0.50%
2007 Note Purchase Agreement [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Percentage of consolidated assets require to maintain			80.00%
Percentage of consolidated revenue required to maintain			80.00%
2007 Note Purchase Agreement [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Consolidated funded indebtedness ratio			350.00%

Schedule of Maturities of Long-Term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Debt Disclosure [Abstract]
2020	$ 36,500
2022	240,000
Thereafter	350,000
Total Debt	$ 626,500	$ 692,714

Schedule of Senior Unsecured Notes Redemption Prices (Detail) - 4.500% Senior Unsecured Notes Due 2026 [Member]	12 Months Ended
	Mar. 31, 2018
2021 [Member]
Debt Instrument Redemption [Line Items]
Redemption price, percentage	102.25%
2022 [Member]
Debt Instrument Redemption [Line Items]
Redemption price, percentage	101.50%
2023 [Member]
Debt Instrument Redemption [Line Items]
Redemption price, percentage	100.75%
2024 and Thereafter [Member]
Debt Instrument Redemption [Line Items]
Redemption price, percentage	100.00%

Amount Outstanding of Tranches - Two Thousand Seven Note Purchase Agreement (Detail) - 2007 Note Purchase Agreement [Member] - Series 2007A Tranche D [Member] $ in Millions	12 Months Ended
	Mar. 31, 2018 USD ($)
Debt Instrument [Line Items]
Principal	$ 36.5
Maturity Date	Oct. 02, 2019
Interest Rate	6.48%

Business Segments - Additional Information (Detail)	12 Months Ended
Business Segments - Additional Information (Detail)	Mar. 31, 2018 Location Facility Terminal Plant Sector Segment JointVentures
Segment Reporting Information [Line Items]
Number of sectors \| Sector	3
Number of reportable business segments \| Segment	5
Cement plant locations \| Location	7
Slag grinding facility \| Facility	1
Cement distribution terminals \| Terminal	18
Gypsum wallboard plants \| Plant	5
Readymix concrete batch plants \| Plant	17
Aggregates processing plants \| Plant	4
Number of frac sand processing facilities \| Facility	2
Number of frac sand drying facilities \| Facility	3
Number of frac sand trans-load locations \| Location	6
Proportionate consolidation of share of Joint Venture's revenue and operating earnings	50.00%
Cement [Member]
Segment Reporting Information [Line Items]
Number of Joint Venture \| JointVentures	1

Financial Information Related to Operations by Segment (Detail) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2018 USD ($) kT	Mar. 31, 2017 USD ($) kT	Mar. 31, 2016 USD ($) kT
Segment Reporting Information [Line Items]
Revenue	$ 284,713	$ 359,371	$ 376,315	$ 366,121	$ 278,663	$ 302,395	$ 332,658	$ 297,504	$ 1,386,520	$ 1,211,220	$ 1,143,492
Less: Joint Venture Revenue									(105,884)	(105,916)	(107,458)
Operating Earnings									382,175	354,431	270,700
Corporate General and Administrative Expense									(41,205)	(33,940)	(37,193)
Legal Settlements									45,098
Other Non-Operating Income									3,728	2,139	2,328
Acquisition and Litigation Expense										5,480
Earnings Before Interest and Income Taxes									299,600	317,150	235,835
Interest Expense, Net									(27,638)	(22,631)	(16,583)
Earnings before Income Taxes	48,725	$ 51,388	$ 92,319	$ 79,530	54,181	$ 83,689	$ 89,373	$ 67,276	271,962	294,519	219,252
Capital Expenditures									131,957	56,938	89,563
Depreciation, Depletion and Amortization									114,015	91,791	97,105
Identifiable Assets	2,368,003				2,247,124				2,368,003	2,247,124	1,883,635
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue									1,580,528	1,396,252	1,324,812
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue									(88,124)	(79,116)	(73,862)
Other [Member]
Segment Reporting Information [Line Items]
Operating Earnings									284
Capital Expenditures									461	697
Identifiable Assets	104,367				22,018				104,367	22,018	27,616
Cement [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue									$ 651,750	$ 566,321	$ 528,499
Cement Sales Volume \| kT									5,365	4,871	4,778
Operating Earnings									$ 179,151	$ 153,525	$ 137,854
Capital Expenditures									45,088	32,790	20,262
Depreciation, Depletion and Amortization									50,891	36,727	33,400
Identifiable Assets	1,247,504				1,234,617				$ 1,247,504	$ 1,234,617	$ 819,994
Cement [Member] \| Operating Segments [Member] \| Wholly-Owned [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume \| kT									4,453	3,934	3,903
Operating Earnings									$ 135,732	$ 111,139	$ 98,771
Cement [Member] \| Operating Segments [Member] \| Joint Venture [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume \| kT									912	937	875
Operating Earnings									$ 43,419	$ 42,386	$ 39,083
Cement [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue									(16,442)	(15,781)	(13,939)
Concrete and Aggregates [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue									157,013	154,592	128,073
Operating Earnings									17,854	18,072	9,807
Capital Expenditures									4,977	6,528	18,783
Depreciation, Depletion and Amortization									7,931	7,931	6,260
Identifiable Assets	104,851				110,413				104,851	110,413	106,634
Concrete and Aggregates [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue									(1,335)	(1,262)	(922)
Gypsum Wallboard [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue									491,779	473,651	461,457
Operating Earnings									158,551	159,866	159,352
Capital Expenditures									19,382	11,393	4,832
Depreciation, Depletion and Amortization									18,179	18,728	19,988
Identifiable Assets	386,041				379,414				386,041	379,414	392,523
Paperboard [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue									181,742	167,065	149,192
Operating Earnings									32,758	37,601	32,153
Capital Expenditures									5,177	3,996	5,542
Depreciation, Depletion and Amortization									8,694	8,425	8,312
Identifiable Assets	123,819				124,356				123,819	124,356	127,371
Paperboard [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue									(70,347)	(62,073)	(59,001)
Oil and Gas Proppants [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue									85,496	34,623	57,591
Operating Earnings									(6,423)	(14,633)	(68,466)
Capital Expenditures									56,872	1,534	40,144
Depreciation, Depletion and Amortization									25,687	18,255	27,227
Identifiable Assets	$ 401,421				$ 376,306				401,421	376,306	409,497
Other [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue									12,748
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization									$ 2,633	$ 1,725	$ 1,918

Segment Breakdown of Goodwill (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Goodwill	$ 205,211	$ 198,370
Cement [Member]
Segment Reporting Information [Line Items]
Goodwill	74,214	74,214
Gypsum Wallboard [Member]
Segment Reporting Information [Line Items]
Goodwill	116,618	116,618
Paperboard [Member]
Segment Reporting Information [Line Items]
Goodwill	7,538	$ 7,538
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Goodwill	$ 6,841

Summarized Financial Information for Joint Venture Unconsolidated (Detail) - Joint Venture [Member] - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Related Party Transaction [Line Items]
Revenue	$ 216,533	$ 215,569
Gross Margin	91,647	90,098
Earnings Before Income Taxes	86,838	84,772
Current Assets	71,089	73,767
Non-Current Assets	66,856	42,337
Current Liabilities	$ 20,671	$ 22,293

Schedule of Components of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Current Provision (Benefit) - Federal	$ 58,695	$ 86,459	$ 64,256
Current Provision (Benefit) - State	5,989	7,638	4,727
Current Provision (Benefit) - Total	64,684	94,097	68,983
Deferred Provision (Benefit) - Federal	(52,333)	7,274	(546)
Deferred Provision (Benefit) - State	2,979	(5,071)	(1,777)
Deferred Provision (Benefit) - Total	(49,354)	2,203	(2,323)
Provision for Income Taxes	$ 15,330	$ 96,300	$ 66,660

Schedule of Effective Tax Rates Vary from Federal Statutory Rates (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Earnings Before Income Taxes	$ 48,725	$ 51,388	$ 92,319	$ 79,530	$ 54,181	$ 83,689	$ 89,373	$ 67,276	$ 271,962	$ 294,519	$ 219,252
Income Taxes at Statutory Rate									85,804	103,082	76,738
Increases (Decreases) in Tax Resulting from - State Income Taxes, net									6,139	1,668	1,166
Increases (Decreases) in Tax Resulting from - Statutory Depletion in Excess of Cost									(6,341)	(1,216)	(5,672)
Increases (Decreases) in Tax Resulting from - Domestic Production Activities Deduction									(5,995)	(7,615)	(6,302)
Increases (Decreases) in Tax Resulting from - Excess Tax Benefit from Stock Compensation									(4,129)
Increases (Decreases) in Tax Resulting from - Meals and Entertainment Disallowance									567	626	629
Increases (Decreases) in Tax Resulting from - Limitation on Officer's Compensation									246
Increases (Decreases) in Tax Resulting from - Impact of Tax Cuts and Jobs Act of 2017									(61,692)
Increases (Decreases) in Tax Resulting from - Other									731	(245)	101
Provision for Income Taxes									$ 15,330	$ 96,300	$ 66,660
Effective Tax Rate									6.00%	33.00%	30.00%

Schedule of Components of Deferred Income Taxes (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Items Giving Rise to Deferred Tax Liabilities - Excess Tax Depreciation and Amortization	$ (106,367)	$ (161,204)
Items Giving Rise to Deferred Tax Liabilities - Depletion	(11,069)	(18,638)
Items Giving Rise to Deferred Tax Liabilities - State Income Taxes, net	(14,265)	(11,455)
Items Giving Rise to Deferred Tax Liabilities - Other	(5,957)	(8,515)
Items Giving Rise to Deferred Tax Liabilities - Total Deferred Tax Liabilities	(137,658)	(199,812)
Items Giving Rise to Deferred Tax Assets - Change in Accruals	8,965	12,992
Items Giving Rise to Deferred Tax Assets - Inventory	4,276	1,242
Items Giving Rise to Deferred Tax Assets - Bad Debts	1,891	3,895
Items Giving Rise to Deferred Tax Assets - Long-term Incentive Compensation Plan	4,616	8,691
Items Giving Rise to Deferred Tax Assets - Credits and Other Carryforwards	12,879	13,103
Items Giving Rise to Deferred Tax Assets - Pension	1,108	4,178
Items Giving Rise to Deferred Tax Assets - Other		218
Items Giving Rise to Deferred Tax Assets - Subtotal	33,735	44,319
Items Giving Rise to Deferred Tax Assets - Valuation Allowance	(15,043)	(10,531)
Items Giving Rise to Deferred Tax Assets - Total Deferred Tax Assets	$ 18,692	$ 33,788

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Income Tax [Line Items]
Uncertain tax positions	$ 0		$ 0	$ 0	$ 0
Federal corporate tax rate	21.00%		31.55%
Provisional benefit for re-measurement of deferred tax liabilities		$ 61,000,000
Additional benefit due to re-measurement of deferred tax liabilities	$ 700,000
Total benefit due to re-measurement of deferred tax liabilities			$ 61,700,000
State Income Tax [Member]
Income Tax [Line Items]
Net operating loss carryforward	1,500,000		1,500,000
Investment credits	$ 14,900,000		$ 14,900,000

Commitments and Contingencies - Additional Information (Detail) - USD ($)					12 Months Ended
	May 08, 2018	Jan. 05, 2018	Jul. 28, 2016	Jun. 16, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2014
Commitments And Contingencies [Line Items]
Letters of credit outstanding, amount					$ 7,500,000
Contingently liable for performance, current						$ 26,100,000
Outstanding guarantees						$ 0
Percentage of expected natural gas usage						25.00%
Operating leases Rental expense					12,000,000	$ 11,300,000	$ 10,300,000
USG Corporation and United States Gypsum [Member]
Commitments And Contingencies [Line Items]
Litigation settlement amount								$ 48,000,000
Temple Inland Inc. [Member]
Commitments And Contingencies [Line Items]
Litigation settlement amount								$ 7,000,000
Lafarge North America [Member] \| Direct Purchaser Class [Member]
Commitments And Contingencies [Line Items]
Litigation settlement amount				$ 23,000,000
Lafarge North America [Member] \| Indirect Purchaser Class [Member]
Commitments And Contingencies [Line Items]
Litigation settlement amount			$ 5,200,000
American Gypsum Company LLC [Member] \| Homebuilder Settlement Agreement [Member] \| Subsequent Event [Member]
Commitments And Contingencies [Line Items]
Litigation settlement amount	$ 6,000,000
American Gypsum Company LLC [Member] \| Direct and Indirect Purchaser Class [Member] \| Direct and Indirect Purchaser Settlement Agreements [Member]
Commitments And Contingencies [Line Items]
Litigation settlement amount		$ 39,100,000
Amount deposited to qualified settlement fund					$ 38,800,000

Schedule of Minimum Annual Rental Commitments (Detail) $ in Thousands	Mar. 31, 2017 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 11,386
2020	8,235
2021	4,807
2022	3,359
2023	2,979
Thereafter	$ 5,596

Stock Option Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2017	May 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Aug. 07, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			4,176,195			3,000,000
Stock option expense			$ 4.3	$ 5.3	$ 7.5
Aggregate intrinsic value for outstanding options			29.3
Aggregate intrinsic value of exercisable options			23.8
Total intrinsic value of options exercised			18.7
Restricted stock or unit expense			$ 9.6	$ 6.8	$ 9.8
Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant						1,500,000
Performance Vesting Stock Options [Member] \| Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		58,055
Percentage of average return on invested capital			17.20%
Reduced percentage of shares earned in stock options plan			66.70%
Shares earned			55,858
Stock based compensation plan, description			The performance criterion for the Fiscal 2018 Employee Performance Stock Option Grant is based upon the achievement of certain levels of return on equity (as defined in the option agreements), ranging from 11.0% to 18.0%, for the fiscal year ending March 31, 2018. All stock options will be earned if the return on equity is 18.0% or greater, and the percentage of shares earned will be reduced proportionately to approximately 66.7% if the return on equity is 11.0%. If the Company does not achieve a return on equity of at least 11.0%, all stock options granted will be forfeited. During fiscal 2018, the adjusted return on equity was approximately 17.2%; therefore, 55,858 options were earned, with the remaining options forfeited.
Share-based compensation vesting period		4 years
Share-based compensation award expiration term		10 years
Performance Vesting Stock Options [Member] \| Long Term Compensation Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital		11.00%
Share-based compensation expiration date			Mar. 31, 2019
Performance Vesting Stock Options [Member] \| Long Term Compensation Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital		18.00%
Share-based compensation expiration date			Mar. 31, 2021
Time Vesting Stock Options [Member] \| Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		48,379
Share-based compensation vesting period		4 years
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost, stock options			$ 6.8
Weighted-average period of recognition of unrecognized compensation cost			2 years 6 months
Stock Options [Member] \| Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation award expiration term		10 years
Board of Directors Stock Option [Member] \| Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant	6,052
Performance Vesting Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		52,646
Percentage of average return on invested capital			17.20%
Shares earned			50,656
Stock based compensation plan, description			The performance criterion for the Fiscal 2018 Employee Restricted Stock Performance Award is based upon the achievement of certain levels of return on equity (as defined in the agreement), ranging from 11.0% to 18.0%, for the fiscal year ended March 31, 2018. All restricted shares will be earned if the return on equity is 18.0% or greater, and the percentage of shares earned will be reduced proportionately to approximately 66.7% if the return on equity is 11.0%. If the Company does not achieve a return on equity of at least 11.0%, all awards will be forfeited.
Share-based compensation vesting period		4 years
Reduced percentage of restricted shares			66.70%
Performance Vesting Restricted Stock [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital		11.00%
Share-based compensation vesting date			Mar. 31, 2019
Performance Vesting Restricted Stock [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital		18.00%
Share-based compensation vesting date			Mar. 31, 2021
Time Vesting Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		43,874
Share-based compensation vesting period		4 years
Time Vesting Restricted Stock [Member] \| Board of Director [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation vesting period		6 months
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant	11,444		330,000
Share-based compensation vesting period	6 months
Weighted-average period of recognition of unrecognized compensation cost			2 years 3 months 18 days
Weighted average grant date fair value, shares granted			$ 100.05	$ 76.67	$ 81.30
Unrecognized compensation cost			$ 17.0
Restricted Stock And Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			1,386,296

Weighted-Average Assumptions Used to Value Option Awards (Detail) - Long Term Compensation Plan [Member] - Stock Options [Member]	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend Yield	1.30%	1.30%
Expected Volatility	36.30%	36.50%
Risk Free Interest Rate	2.10%	1.40%
Expected Life	6 years	6 years

Stock Option Activity (Detail) - $ / shares	12 Months Ended
Stock Option Activity (Detail) - $ / shares	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding Options at Beginning of Year	1,323,379	1,817,763	1,665,565
Number of Shares, Granted	119,986	202,364	318,572
Number of Shares, Exercised	(448,295)	(677,566)	(137,874)
Number of Shares, Cancelled	(36,934)	(19,182)	(28,500)
Number of Shares, Outstanding Options at End of Year	958,136	1,323,379	1,817,763
Number of Shares, Options Exercisable at End of Year	651,218	874,116	1,285,412
Weighted-Average Exercise Price, Outstanding Options at Beginning of Year	$ 66.07	$ 53.03	$ 46.37
Weighted-Average Exercise Price, Granted	100.20	77.76	79.83
Weighted-Average Exercise Price, Exercised	60.27	34.46	27.58
Weighted-Average Exercise Price, Cancelled	79.97	70.30	86.35
Weighted-Average Exercise Price, Outstanding Options at End of Year	72.52	66.07	53.03
Weighted Average Fair Value of Options Granted during the Year	$ 33.37	$ 25.22	$ 24.27

Stock Options Outstanding (Detail)	12 Months Ended
Stock Options Outstanding (Detail)	Mar. 31, 2018 $ / shares shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding, Number of Shares Outstanding \| shares	958,136
Options Outstanding, Weighted-Average Remaining Contractual Life	6 years 7 months 24 days
Options Outstanding, Weighted-Average Exercise Price	$ 72.52
Options Exercisable , Number of Shares Outstanding \| shares	651,218
Options Exercisable, Weighted-Average Exercise Price	$ 66.53
$23.17 - $29.84 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	23.17
Range of Exercise Prices, Upper Range	$ 29.84
Options Outstanding, Number of Shares Outstanding \| shares	65,912
Options Outstanding, Weighted-Average Remaining Contractual Life	3 years 4 months 6 days
Options Outstanding, Weighted-Average Exercise Price	$ 23.27
Options Exercisable , Number of Shares Outstanding \| shares	65,912
Options Exercisable, Weighted-Average Exercise Price	$ 23.27
$33.43 - $ 37.34 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	33.43
Range of Exercise Prices, Upper Range	$ 37.34
Options Outstanding, Number of Shares Outstanding \| shares	99,582
Options Outstanding, Weighted-Average Remaining Contractual Life	4 years 2 months 15 days
Options Outstanding, Weighted-Average Exercise Price	$ 33.94
Options Exercisable , Number of Shares Outstanding \| shares	99,582
Options Exercisable, Weighted-Average Exercise Price	$ 33.94
$53.22 - $ 77.67 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	53.22
Range of Exercise Prices, Upper Range	$ 77.67
Options Outstanding, Number of Shares Outstanding \| shares	307,424
Options Outstanding, Weighted-Average Remaining Contractual Life	7 years
Options Outstanding, Weighted-Average Exercise Price	$ 71.12
Options Exercisable , Number of Shares Outstanding \| shares	183,248
Options Exercisable, Weighted-Average Exercise Price	$ 69.79
$79.73 - $ 106.00 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	79.73
Range of Exercise Prices, Upper Range	$ 106.00
Options Outstanding, Number of Shares Outstanding \| shares	485,218
Options Outstanding, Weighted-Average Remaining Contractual Life	7 years 4 months 13 days
Options Outstanding, Weighted-Average Exercise Price	$ 88.02
Options Exercisable , Number of Shares Outstanding \| shares	302,476
Options Exercisable, Weighted-Average Exercise Price	$ 84.72

Summary of Activity for Nonvested Restricted Shares (Detail) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Beginning of Year	371,213
Number of Shares, Granted	107,964
Number of Shares, Vested	(119,187)
Number of Shares, Forfeited	(31,931)
Number of Shares, Nonvested at End of Year	328,059	371,213
Weighted Average Grant Date Fair Value, Beginning of Year	$ 60.33
Weighted Average Grant Date Fair Value, Granted	100.05	$ 76.67	$ 81.30
Weighted Average Grant Date Fair Value, Vested	80.04
Weighted Average Grant Date Fair Value, Forfeited	40.00
Weighted Average Grant Date Fair Value, Nonvested at End of Year	$ 65.76	$ 60.33

Net Interest Expense, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
Net Interest Expense, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Interest Income (Expense), Net [Abstract]
Interest Income	$ (14)	$ (40)	$ (6)
Interest Expense	26,433	21,595	15,891
Other Expenses	1,219	1,076	698
Interest Expense, net	$ 27,638	$ 22,631	$ 16,583

Schedule of Reconciliation of Obligations and Fair Values of Plan Assets (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Benefit Obligation at April 1,		$ 40,589	$ 42,281
Service Cost - Benefits Earned During the Period		710	1,001	$ 1,039
Interest Cost on Projected Benefit Obligation		1,466	1,584	1,525
Amendments			199
Actuarial (Gain) Loss		(4,505)	(3,531)
Settlement	$ (3,900)	(3,857)
Benefits Paid		(1,033)	(945)
Benefit Obligation at March 31,	33,370	33,370	40,589	42,281
Fair Value of Plan Assets at April 1,		26,410	21,424
Actual Return on Plan Assets		2,805	2,522
Employer Contributions		9,087	3,409
Settlement		(3,857)
Benefits Paid		(1,033)	(945)
Fair Value of Plans at March 31,	33,412	33,412	26,410	$ 21,424
Funded (Unfunded) Status at March 31,	42	42	(14,179)
Prepaid and Other Assets	538	538
Accrued Benefit Liability	(496)	(496)	(14,179)
Accumulated Other Comprehensive Losses:	5,278	5,278	11,936
Accumulated Other Comprehensive Losses - Net Actuarial Loss	5,198	5,198	11,587
Accumulated Other Comprehensive Losses - Prior Service Cost	80	80	349
Accumulated Other Comprehensive Losses	5,278	5,278	11,936
Reclassification to Retained Earnings	978	978
Tax impact	(2,244)	(2,244)	(4,540)
Accumulated Other Comprehensive Losses, net of tax	$ 4,012	$ 4,012	$ 7,396

Summary of Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Projected Benefit Obligation	$ 33,370	$ 40,589	$ 42,281
Accumulated Benefit Obligation	33,367	40,391
Fair Value of Plan Assets	$ 33,412	$ 26,410	$ 21,424

Components of Net Periodic Cost (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Service Cost - Benefits Earned During the Period		$ 710	$ 1,001	$ 1,039
Interest Cost of Projected Benefit Obligation		1,466	1,584	1,525
Expected Return on Plan Assets		(2,137)	(1,606)	(1,751)
Recognized Net Actuarial Loss		566	1,712	1,773
Amortization of Prior-Service Cost		269	359	300
Settlement	$ 600	649
Net Periodic Pension Cost		$ 1,523	$ 3,050	$ 2,886

Pension and Profit Sharing Plans - Additional information (Detail) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($) Employee CompensationPlan	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, payments for settlement	$ 3,900		$ 3,857
Settlement cost	600		$ 649
Expected return on plan assets			7.50%	7.50%	8.00%
Costs relating to employer discretionary contributions			$ 8,400	$ 6,400	$ 6,200
Current actuarial estimates contributions			$ 600	300	300
Number of employees covered under multi-employer pension plans \| Employee			60
Number of multi-employer plans \| CompensationPlan			3
Collective bargaining agreement for employer covered under multi-employer plans, Expiration ending date			Mar. 31, 2020
Expenses related to Multi employer plans			$ 1,600	$ 1,600	$ 1,300
Salaried Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Employees fully vesting in employer's own contributions made beginning in 2007, requirement years			6 years
Hourly Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Employees fully vesting in employer's own contributions made beginning in 2007, requirement years			3 years
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Current actuarial estimates contributions for fiscal year 2018	2,500		$ 2,500
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Current actuarial estimates contributions for fiscal year 2018	$ 3,000		$ 3,000
Scenario Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets		6.00%
Expenses related to Multi employer plans		$ 1,800

Schedule of Expected Benefit Payments (Detail) $ in Thousands	Mar. 31, 2018 USD ($)
Compensation And Retirement Disclosure [Abstract]
2019	$ 1,350
2020	1,416
2021	1,520
2022	1,604
2023	1,657
2024-2028	$ 9,412

Schedule of Assumptions Used in Net Periodic Benefit Cost and Benefit Obligations (Detail)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Net Periodic Benefit Costs - Discount Rate	4.03%	3.83%	3.70%
Net Periodic Benefit Costs - Expected Return on Plan Assets	7.50%	7.50%	8.00%
Net Periodic Benefit Costs - Rate of Compensation Increase	3.50%	3.50%	3.50%
Benefit Obligations - Discount Rate	4.12%	4.03%
Benefit Obligations - Rate of Compensation Increase	3.50%	3.50%

Schedule of Pension Plans Weighted-Average Asset Allocation and Range of Target Allocation (Detail)	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at March 31	100.00%	100.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at March 31	50.00%	70.00%
Equity Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation	40.00%
Equity Securities [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation	60.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at March 31	47.00%	27.00%
Debt Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation	35.00%
Debt Securities [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation	60.00%
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at March 31	3.00%	3.00%
Other [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation	0.00%
Other [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of Target Allocation	5.00%

Schedule of Fair Values of Defined Benefit Plans (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	$ 33,412	$ 26,410	$ 21,424
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	16,533	18,375
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	15,799	7,166
Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	163	147
Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	704	258
Commodity Linked Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	$ 213	$ 464

Schedule of Fair Values of Defined Benefit Plans Determined Using Fair Value Hierarchy of Inputs (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	$ 33,412	$ 26,410	$ 21,424
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	16,533	18,375
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	15,799	7,166
Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	163	147
Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	704	258
Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	704	258
Fair Value, Inputs, Level 1 \| Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	704	258
Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	32,708	26,152
Fair Value, Inputs, Level 2 \| Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	16,533	18,375
Fair Value, Inputs, Level 2 \| Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	15,799	7,166
Fair Value, Inputs, Level 2 \| Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	163	147
Commodity Linked Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	213	464
Commodity Linked Funds [Member] \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plans	$ 213	$ 464

Condensed Consolidating Statement of Earnings and Comprehensive Earnings (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Revenue	$ 284,713	$ 359,371	$ 376,315	$ 366,121	$ 278,663	$ 302,395	$ 332,658	$ 297,504	$ 1,386,520	$ 1,211,220	$ 1,143,492
Cost of Goods Sold									1,047,764	899,175	911,875
Gross Profit	61,377	94,566	96,754	86,059	61,500	87,380	91,210	71,955	338,756	312,045	231,617
Equity in Earnings of Unconsolidated Joint Venture									43,419	42,386	39,083
Corporate General and Administrative Expense									(41,205)	(33,940)	(37,193)
Legal Settlements									(45,098)
Other Non-Operating Income									3,728	2,139	2,328
Acquisition-Related Expense										(5,480)
Interest Expense, net									(27,638)	(22,631)	(16,583)
Earnings before Income Taxes	48,725	51,388	92,319	79,530	54,181	83,689	89,373	67,276	271,962	294,519	219,252
Income Taxes									(15,330)	(96,300)	(66,660)
Net Earnings	$ 37,008	$ 101,380	$ 63,362	$ 54,882	$ 36,251	$ 56,387	$ 60,237	$ 45,344	256,632	198,219	152,592
Net Actuarial Change in Benefit Plans, net of tax									3,384	4,013	658
Comprehensive Earnings									260,016	202,232	153,250
Eliminations [Member]
Equity in Earnings of Unconsolidated Joint Venture									(43,419)	(42,386)	(39,083)
Equity in Earnings of Subsidiaries									(289,950)	(210,923)	(160,018)
Earnings before Income Taxes									(333,369)	(253,309)	(199,101)
Net Earnings									(333,369)	(253,309)	(199,101)
Net Actuarial Change in Benefit Plans, net of tax									(3,384)	(4,013)	(658)
Comprehensive Earnings									(336,753)	(257,322)	(199,759)
Parent [Member]
Equity in Earnings of Unconsolidated Joint Venture									43,419	42,386	39,083
Equity in Earnings of Subsidiaries									289,950	210,923	160,018
Corporate General and Administrative Expense									(37,825)	(28,545)	(32,047)
Legal Settlements									(45,098)
Other Non-Operating Income									(233)	(534)	(398)
Acquisition-Related Expense										(5,480)
Interest Expense, net									(27,609)	(51,315)	(39,038)
Earnings before Income Taxes									222,604	167,435	127,618
Income Taxes									34,028	30,784	24,974
Net Earnings									256,632	198,219	152,592
Net Actuarial Change in Benefit Plans, net of tax									3,384	4,013	658
Comprehensive Earnings									260,016	202,232	153,250
Guarantor Subsidiaries [Member]
Revenue									1,386,520	1,211,220	1,143,492
Cost of Goods Sold									1,047,764	899,175	911,875
Gross Profit									338,756	312,045	231,617
Equity in Earnings of Unconsolidated Joint Venture									43,419	42,386	39,083
Corporate General and Administrative Expense									(3,380)	(5,395)	(5,146)
Other Non-Operating Income									3,961	2,673	2,726
Acquisition-Related Expense										0
Interest Expense, net									(29)	28,684	22,455
Earnings before Income Taxes									382,727	380,393	290,735
Income Taxes									(49,358)	(127,084)	(91,634)
Net Earnings									333,369	253,309	199,101
Net Actuarial Change in Benefit Plans, net of tax									3,384	4,013	658
Comprehensive Earnings									$ 336,753	$ 257,322	$ 199,759

Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Current Assets -
Cash and Cash Equivalents	$ 9,315	$ 6,561
Restricted Cash	38,753
Accounts and Notes Receivable	141,685	136,313
Inventories	258,159	252,846
Income Tax Receivable	5,750
Prepaid and Other Current Assets	5,073	4,904
Total Current Assets	458,735	400,624
Property, Plant, and Equipment -	2,586,528	2,439,438
Less: Accumulated Depreciation	(991,229)	(892,601)
Property, Plant, and Equipment, net	1,595,299	1,546,837
Notes Receivable	115	815
Investment in Joint Venture	60,558	48,620
Goodwill and Intangible Assets, net	239,342	235,505
Other Assets	13,954	14,723
Total Assets	2,368,003	2,247,124	$ 1,883,635
Current Liabilities -
Accounts Payable	73,459	92,193
Accrued Liabilities	105,870	55,379
Income Tax Payable		733
Current Portion of Long-term Debt		81,214
Total Current Liabilities	179,329	229,519
Long-term Debt	620,922	605,253
Other Long-term Liabilities	31,096	42,878
Deferred Income Taxes	118,966	166,024
Total Liabilities	950,313	1,043,674
Total Stockholders’ Equity	1,417,690	1,203,450	$ 1,040,531	$ 1,010,593
Liabilities and Stockholders' Equity, Total	2,368,003	2,247,124
Eliminations [Member]
Current Assets -
Income Tax Receivable	(103,760)	(33,196)
Total Current Assets	(103,760)	(33,196)
Investments in Subsidiaries and Receivables from Affiliates	(3,481,149)	(8,378,598)
Total Assets	(3,584,909)	(8,411,794)
Current Liabilities -
Income Tax Payable	(103,760)	(33,196)
Total Current Liabilities	(103,760)	(33,196)
Payables to Affiliates	(6,370,576)	(6,078,019)
Total Liabilities	(6,474,336)	(6,111,215)
Total Stockholders’ Equity	2,889,427	(2,300,579)
Liabilities and Stockholders' Equity, Total	(3,584,909)	(8,411,794)
Parent [Member]
Current Assets -
Cash and Cash Equivalents	5,784	5,184
Restricted Cash	38,753
Accounts and Notes Receivable	407	422
Income Tax Receivable	109,510	33,196
Prepaid and Other Current Assets	665	484
Total Current Assets	155,119	39,286
Property, Plant, and Equipment -	3,188	2,914
Less: Accumulated Depreciation	(1,089)	(937)
Property, Plant, and Equipment, net	2,099	1,977
Investment in Joint Venture	70	51
Investments in Subsidiaries and Receivables from Affiliates	2,718,809	5,126,289
Other Assets	5,417	5,687
Total Assets	2,881,514	5,173,290
Current Liabilities -
Accounts Payable	5,591	6,687
Accrued Liabilities	67,387	21,043
Income Tax Payable		733
Current Portion of Long-term Debt		81,214
Total Current Liabilities	72,978	109,677
Long-term Debt	620,922	605,253
Other Long-term Liabilities	124	189
Payables to Affiliates	762,340	3,252,309
Deferred Income Taxes	7,460	2,412
Total Liabilities	1,463,824	3,969,840
Total Stockholders’ Equity	1,417,690	1,203,450
Liabilities and Stockholders' Equity, Total	2,881,514	5,173,290
Guarantor Subsidiaries [Member]
Current Assets -
Cash and Cash Equivalents	3,531	1,377
Accounts and Notes Receivable	141,278	135,891
Inventories	258,159	252,846
Prepaid and Other Current Assets	4,408	4,420
Total Current Assets	407,376	394,534
Property, Plant, and Equipment -	2,583,340	2,436,524
Less: Accumulated Depreciation	(990,140)	(891,664)
Property, Plant, and Equipment, net	1,593,200	1,544,860
Notes Receivable	115	815
Investment in Joint Venture	60,488	48,569
Investments in Subsidiaries and Receivables from Affiliates	762,340	3,252,309
Goodwill and Intangible Assets, net	239,342	235,505
Other Assets	8,537	9,036
Total Assets	3,071,398	5,485,628
Current Liabilities -
Accounts Payable	67,868	85,506
Accrued Liabilities	38,483	34,336
Income Tax Payable	103,760	33,196
Total Current Liabilities	210,111	153,038
Other Long-term Liabilities	30,972	42,689
Payables to Affiliates	5,608,236	2,825,710
Deferred Income Taxes	111,506	163,612
Total Liabilities	5,960,825	3,185,049
Total Stockholders’ Equity	(2,889,427)	2,300,579
Liabilities and Stockholders' Equity, Total	$ 3,071,398	$ 5,485,628

Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	$ 337,665	$ 331,598	$ 265,767
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment	(131,957)	(56,938)	(89,563)
Acquisition Spending	(36,761)	(400,488)	(32,427)
Net Cash Used in Investing Activities	(168,718)	(457,426)	(121,990)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase (Decrease) in Credit Facility	15,000	(157,000)	52,000
Repayment of Senior Notes	(81,214)	(8,000)	(57,045)
Issuance of Long-term Debt		350,000
Payment of Debt Issuance Costs		(6,637)
Dividends Paid to Stockholders	(19,438)	(19,341)	(20,020)
Purchase and Retirement of Common Stock	(61,078)	(60,013)	(123,530)
Proceeds from Stock Option Exercises	24,264	22,108	2,866
Shares Redeemed to Settle Employee Taxes on Stock Compensation	(4,974)	(4,468)	(4,273)
Excess Tax Benefits from Share Based Payment Arrangements		10,349	4,102
Net Cash Provided by (Used in) Financing Activities	(127,440)	126,998	(145,900)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	41,507	1,170	(2,123)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD	6,561	5,391	7,514
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	48,068	6,561	5,391
Eliminations [Member]
CASH FLOWS FROM INVESTING ACTIVITIES
Investment in Subsidiaries	36,761	400,488	32,427
Net Cash Used in Investing Activities	36,761	400,488	32,427
CASH FLOWS FROM FINANCING ACTIVITIES
Intra-entity Activity, net	(36,761)	(400,488)	(32,427)
Net Cash Provided by (Used in) Financing Activities	(36,761)	(400,488)	(32,427)
Parent [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	(83,947)	(64,376)	(37,985)
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment	(142)	(697)
Investment in Subsidiaries	(36,761)	(400,488)	(32,427)
Net Cash Used in Investing Activities	(36,903)	(401,185)	(32,427)
CASH FLOWS FROM FINANCING ACTIVITIES
Increase (Decrease) in Credit Facility	15,000	(157,000)	52,000
Repayment of Senior Notes	(81,214)	(8,000)	(57,045)
Issuance of Long-term Debt		350,000
Payment of Debt Issuance Costs		(6,637)
Dividends Paid to Stockholders	(19,438)	(19,341)	(20,020)
Purchase and Retirement of Common Stock	(61,078)	(60,013)	(123,530)
Proceeds from Stock Option Exercises	24,264	22,108	2,866
Shares Redeemed to Settle Employee Taxes on Stock Compensation	(4,974)	(4,468)	(4,273)
Excess Tax Benefits from Share Based Payment Arrangements		10,349	4,102
Intra-entity Activity, net	287,643	340,240	216,175
Net Cash Provided by (Used in) Financing Activities	160,203	467,238	70,275
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	39,353	1,677	(137)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD	5,184	3,507	3,644
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	44,537	5,184	3,507
Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	421,612	395,974	303,752
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment	(131,815)	(56,241)	(89,563)
Acquisition Spending	(36,761)	(400,488)	(32,427)
Net Cash Used in Investing Activities	(168,576)	(456,729)	(121,990)
CASH FLOWS FROM FINANCING ACTIVITIES
Intra-entity Activity, net	(250,882)	60,248	(183,748)
Net Cash Provided by (Used in) Financing Activities	(250,882)	60,248	(183,748)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	2,154	(507)	(1,986)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD	1,377	1,884	3,870
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	$ 3,531	$ 1,377	$ 1,884

Quarterly Results (unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 284,713	$ 359,371	$ 376,315	$ 366,121	$ 278,663	$ 302,395	$ 332,658	$ 297,504	$ 1,386,520	$ 1,211,220	$ 1,143,492
Gross Profit	61,377	94,566	96,754	86,059	61,500	87,380	91,210	71,955	338,756	312,045	231,617
Earnings Before Income Taxes	48,725	51,388	92,319	79,530	54,181	83,689	89,373	67,276	271,962	294,519	219,252
Net Earnings	$ 37,008	$ 101,380	$ 63,362	$ 54,882	$ 36,251	$ 56,387	$ 60,237	$ 45,344	$ 256,632	$ 198,219	$ 152,592
Diluted Earnings Per Share	$ 0.76	$ 2.08	$ 1.31	$ 1.13	$ 0.75	$ 1.17	$ 1.25	$ 0.93	$ 5.28	$ 4.10	$ 3.05

Quarterly Results (unaudited) - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018
Effect Of Fourth Quarter Events [Line Items]
Pre-tax expense related to settlement agreement			$ 45,098
Personnel related expenses	$ 4,000
Fairborn Acquisition [Member]
Effect Of Fourth Quarter Events [Line Items]
Transaction related expenses		$ 4,400
Annual maintenance costs		$ 5,000
Homebuilder Settlement Agreement [Member]
Effect Of Fourth Quarter Events [Line Items]
Pre-tax expense related to settlement agreement	$ 6,000

Business Segments - Additional Information (Detail)	12 Months Ended
Business Segments - Additional Information (Detail)	Mar. 31, 2018 Location Facility Terminal Plant Sector Segment JointVentures
Segment Reporting Information [Line Items]
Number of sectors \| Sector	3
Number of reportable business segments \| Segment	5
Cement plant locations \| Location	7
Slag grinding facility \| Facility	1
Cement distribution terminals \| Terminal	18
Gypsum wallboard plants \| Plant	5
Readymix concrete batch plants \| Plant	17
Aggregates processing plants \| Plant	4
Number of frac sand processing facilities \| Facility	2
Number of frac sand drying facilities \| Facility	3
Number of frac sand trans-load locations \| Location	6
Proportionate consolidation of share of Joint Venture's revenue and operating earnings	50.00%
Cement [Member]
Segment Reporting Information [Line Items]
Number of Joint Venture \| JointVentures	1

Fair Value of Senior Notes (Detail) $ in Thousands	Mar. 31, 2018 USD ($)
Series 2007A Tranche D [Member]
Fair Value Of Financial Instruments [Line Items]
Fair Value of Senior Notes	$ 37,849
4.500% Senior Unsecured Notes Due 2026 [Member]
Fair Value Of Financial Instruments [Line Items]
Fair Value of Senior Notes	$ 353,600