Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Cash flows from operating activities
Net income	$ 263,846	$ 203,886	$ 317,903
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	251,174	244,387	220,970
Stock-based compensation	18,129	16,410	18,800
Loss on disposal of assets and impairment charges	3,495	1,384	2,281
Deferred income taxes	49,810	45,337	(98,178)
Changes in assets and liabilities:
Receivables	(10,644)	7,189	(1,801)
Inventories	37,713	(29,648)	(38,406)
Prepaid expenses	(2,308)	(1,727)	3,413
Accounts payable	(140,151)	12,451	14,751
Accrued expenses	26,400	30,927	15,967
Income taxes	15,783	22,545	(30,053)
Other, net	(8,933)	(22,527)	(5,850)
Net cash provided by operating activities	504,314	530,614	419,797
Cash flows from investing activities
Purchase of property and equipment	(438,977)	(394,699)	(577,421)
Payments for acquisitions of businesses, net of cash acquired	(32,706)	(68,200)	(37,160)
Proceeds from sales of property and equipment	5,041	5,069	5,246
Net cash used in investing activities	(466,642)	(457,830)	(609,335)
Cash flows from financing activities
Proceeds from long-term debt	0	0	400,000
Repayments of long-term debt	(17,476)	(16,000)	(15,688)
Net borrowings of short-term debt	45,000	35,400	38,700
Proceeds from exercise of stock options	2,958	2,290	1,377
Payments of cash dividends	(45,951)	(41,430)	(38,780)
Repurchase of common stock	0	(37,479)	(214,683)
Tax withholdings on employee share-based awards	(7,224)	(5,948)	(4,426)
Net cash (used in) provided by financing activities	(22,693)	(63,167)	166,500
Net increase (decrease) in cash and cash equivalents	14,979	9,617	(23,038)
Cash and cash equivalents at beginning of year	63,296	53,679	76,717
Cash and cash equivalents at end of year	78,275	63,296	53,679
SUPPLEMENTAL DISCLOSURES OF CASH FLOWS INFORMATION
Cash paid during the year for interest, net of amount capitalized	54,277	56,306	48,757
Cash paid (received) for income taxes, net	9,364	(11,433)	24,274
Noncash investing and financing activities
Noncash additions from adoption of ASC 842	2,840
Purchased property and equipment in accounts payable	5,328	15,616	12,014
Shares repurchased in accounts payable	$ 0	$ 0	$ 2,232