Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Cash flows from operating activities:
Net income	$ 298,641	$ 147,407
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	163,568	145,682
Stock-based compensation	16,378	7,356
Loss on disposal of assets and impairment charges	2,010	810
Deferred income taxes	(115,552)	27,400
Changes in assets and liabilities:
Receivables	1,737	(6,841)
Inventories	(52,870)	(4,061)
Prepaid expenses	1,982	(1,718)
Accounts payable	(13,341)	(20,755)
Accrued expenses	15,700	19,100
Income taxes	(11,867)	4,594
Other, net	(10,410)	(2,947)
Net cash provided by operating activities	295,976	316,027
Cash flows from investing activities:
Purchase of property and equipment	(426,398)	(325,609)
Payments for acquisition of businesses, net of cash acquired	(26,192)	(13,565)
Proceeds from sales of property and equipment	3,857	2,916
Net cash used in investing activities	(448,733)	(336,258)
Cash flows from financing activities:
Proceeds from long-term debt	400,000	100,000
Repayments of long-term debt	(8,097)	(7,797)
Net repayments of short-term debt	(900)	0
Proceeds from exercise of stock options	801	1,975
Payments of cash dividends	(29,023)	(27,407)
Repurchase of common stock	(144,104)	0
Tax withholdings on employee share-based awards	(3,926)	(6,594)
Net cash provided by financing activities	214,751	60,177
Net increase in cash and cash equivalents	61,994	39,946
Cash and cash equivalents at beginning of the period	76,717	75,775
Cash and cash equivalents at end of the period	138,711	115,721
Cash paid during the period for:
Interest, net of amount capitalized	28,281	24,430
Income taxes, net	24,274	46,861
Noncash investing and financing activities:
Purchased property and equipment in accounts payable	$ 13,700	$ 10,020