Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income (Loss)	$ 463,416	$ 477,639	$ 461,540
Adjustments to Reconcile Net Earnings to Net Cash Provided by Operating Activities, Net of Effect of Noncash Activity:
Depreciation, Depletion, and Amortization	158,902	149,832	138,554
Deferred Income Tax Provision	(4,855)	7,953	4,475
Stock Compensation Expense	18,743	19,900	17,155
Equity in Earnings of Unconsolidated Joint Venture	(26,396)	(31,581)	(35,474)
Distributions from Joint Venture	0	7,000	27,000
Changes in Operating Assets and Liabilities:
Accounts and Notes Receivable	(7,904)	(551)	(12,035)
Inventories	(36,832)	(67,232)	(47,946)
Accounts Payable and Accrued Liabilities	874	13,794	(7,797)
Other Assets	(16,747)	(20,468)	4,955
Income Taxes Receivable	(653)	7,652	(8,701)
Net Cash Provided by Operating Activities	548,548	563,938	541,726
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant, and Equipment	(195,281)	(120,305)	(110,143)
Acquisition Spending	(174,850)	(55,053)	(158,451)
Net Cash Used in Investing Activities	(370,131)	(175,358)	(268,594)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings Under Revolving Credit Facility	335,000	13,000	200,000
Repayment of Borrowings Under Revolving Credit Facility	(305,000)	0	(43,000)
Borrowings Under Term Loan	125,000
Repayment of Term Loan	(11,250)	(10,000)	(7,500)
Dividends Paid to Stockholders	(33,722)	(35,298)	(37,496)
Purchase and Retirement of Common Stock	(298,286)	(343,274)	(387,717)
Payment of Excise Tax on Purchases and Retirement of Common Stock	(3,331)	0	0
Proceeds from Stock Option Exercises	6,380	17,098	5,418
Payment of Debt Issuance Costs	(1,834)	0	(903)
Shares Redeemed to Settle Employee Taxes on Stock Compensation	(5,898)	(10,423)	(6,108)
Net Cash Used in Financing Activities	(192,941)	(368,897)	(277,306)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(14,524)	19,683	(4,174)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	34,925	15,242	19,416
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 20,401	$ 34,925	$ 15,242