Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Cash flows from operating activities
Net income	$ 180,628	$ 126,820	$ 103,814
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	156,111	131,160	111,823
Other amortization	319	297	195
Stock-based compensation	7,307	5,600	4,270
Loss on disposal of assets and impairment charges	2,370	2,846	4,788
Deferred income taxes	44,711	17,089	31,828
Excess tax benefits related to stock option exercises	(3,624)	(1,791)	(1,929)
Changes in assets and liabilities:
Receivables	3,232	(4,941)	800
Inventories	10,365	(13,696)	(16,222)
Prepaid expenses	(547)	(82)	(98)
Accounts payable	(33,290)	17,894	21,748
Accrued expenses	(17,544)	33,818	15,783
Income taxes receivable	(7,801)	(441)	9,969
Other, net	(555)	(413)	(441)
Net cash provided by operating activities	341,682	314,160	286,328
Cash flows from investing activities
Purchase of property and equipment	(360,734)	(308,633)	(305,301)
Payments for acquisitions of businesses, net of cash acquired	(41,157)	(31,584)	(29,527)
Proceeds from sales of property and equipment	2,748	3,328	3,544
Net cash used in investing activities	(399,143)	(336,889)	(331,284)
Cash flows from financing activities
Proceeds from long-term debt	0	200,000	0
Repayments of long-term debt	(553)	(15,865)	(10,757)
Net (repayments) borrowings of short-term debt	0	(59,100)	59,100
Proceeds from exercise of stock options	11,465	3,368	4,721
Payments of cash dividends	(30,175)	(27,095)	(24,685)
Excess tax benefits related to stock option exercises	3,624	1,791	1,929
Net cash (used in) provided by financing activities	(15,639)	103,099	30,308
Net (decrease) increase in cash and cash equivalents	(73,100)	80,370	(14,648)
Cash and cash equivalents at beginning of year	121,641	41,271	55,919
Cash and cash equivalents at end of year	48,541	121,641	41,271
SUPPLEMENTAL DISCLOSURES OF CASH FLOWS INFORMATION
Cash paid during the year for interest, net of amount capitalized	41,382	36,923	35,226
Cash paid for income taxes, net	64,367	50,031	17,973
Noncash investing and financing activities
Purchased property and equipment in accounts payable	9,060	5,056	4,020
Property and equipment acquired through notes payable and capitalized lease obligations	$ 0	$ 1,169	$ 981