Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Cash flows from operating activities:
Net income	$ 178,674	$ 298,641
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	181,520	163,568
Stock-based compensation	11,111	16,378
Loss on disposal of assets and impairment charges	1,159	2,010
Deferred income taxes	38,925	(115,552)
Changes in assets and liabilities:
Receivables	4,146	1,737
Inventories	(8,252)	(52,870)
Prepaid expenses	(3,986)	1,982
Accounts payable	(76,788)	(13,341)
Accrued expenses	22,772	15,700
Income taxes	36,685	(11,867)
Other, net	(18,052)	(10,410)
Net cash provided by operating activities	367,914	295,976
Cash flows from investing activities:
Purchase of property and equipment	(301,323)	(426,398)
Payments for acquisition of businesses, net of cash acquired	(21,021)	(26,192)
Proceeds from sales of property and equipment	4,159	3,857
Net cash used in investing activities	(318,185)	(448,733)
Cash flows from financing activities:
Proceeds from long-term debt	0	400,000
Repayments of long-term debt	(7,839)	(8,097)
Net borrowings (repayments) of short-term debt	10,400
Net borrowings (repayments) of short-term debt		(900)
Proceeds from exercise of stock options	1,168	801
Payments of cash dividends	(30,808)	(29,023)
Repurchase of common stock	(37,479)	(144,104)
Tax withholdings on employee share-based awards	(4,681)	(3,926)
Net cash (used in) provided by financing activities	(69,239)	214,751
Net (decrease) increase in cash and cash equivalents	(19,510)	61,994
Cash and cash equivalents at beginning of the period	53,679	76,717
Cash and cash equivalents at end of the period	34,169	138,711
Cash paid (received) during the period for:
Interest, net of amount capitalized	33,354	28,281
Income taxes, net	(21,977)	24,274
Noncash investing and financing activities:
Purchased property and equipment in accounts payable	1,472	13,700
Shares repurchased in accounts payable	$ 0	$ 575