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