Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net Earnings	$ 339,444	$ 70,894	$ 68,860
Adjustments to Reconcile Net Earnings to Net Cash Provided by Operating Activities, Net of Effect of Non-Cash Activity:
Depreciation, Depletion, and Amortization	129,087	113,518	122,535
Impairment Losses		224,267	220,265
Deferred Income Tax Provision	59,319	75,987	(28,371)
Stock Compensation Expense	15,293	19,823	15,109
Gain on Sale of Businesses	(61,203)
Equity in Earnings of Unconsolidated Joint Venture	(37,441)	(42,585)	(38,565)
Distributions from Joint Venture	36,000	33,500	34,250
Changes in Operating Assets and Liabilities:
Accounts and Notes Receivable	2,127	(25,005)	10,180
Inventories	30,002	26,729	(19,016)
Accounts Payable and Accrued Liabilities	9,541	17,265	(31,949)
Other Assets	(6,455)	7,841	(3,284)
Income Taxes Receivable	127,359	(122,933)	270
Net Cash Provided by Operating Activities	643,073	399,301	350,284
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment	(53,933)	(132,119)	(168,873)
Acquisition Spending		(699,361)
Proceeds from Sale of Businesses	91,022
Proceeds from Sales of Property, Plant, and Equipment		400	2,281
Net Cash Provided by (Used in) Investing Activities	37,089	(831,080)	(166,592)
CASH FLOWS FROM FINANCING ACTIVITIES
(Decrease) Increase in Revolving Credit Facility	(560,000)	250,000	70,000
Repayment of Private Placement Senior Unsecured Notes		(36,500)
Issuance of Term Loan		665,000
Dividends Paid to Stockholders	(4,163)	(17,142)	(18,927)
Purchase and Retirement of Common Stock		(313,887)	(271,988)
Proceeds from Stock Option Exercises	40,455	3,298	2,103
Shares Redeemed to Settle Employee Taxes on Stock Compensation	(4,186)	(4,063)	(4,347)
Payment of Debt Issuance Costs	(2,396)	(4,880)
Net Cash (Used in) Provided by Financing Activities	(530,290)	541,826	(223,159)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	149,872	110,047	(39,467)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT BEGINNING OF PERIOD	118,648	8,601	48,068
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT END OF PERIOD	$ 268,520	$ 118,648	$ 8,601