Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Cash flows from operations:
Net income	$ 71,890	$ 77,023
Adjustments to reconcile net income to net cash provided by operations
Depreciation and amortization	53,684	46,327
Other amortization	116	389
Stock based compensation	2,060	1,521
Loss on sale and disposal of property and equipment	3,387	848
Deferred income taxes	20,226	26,140
Excess tax benefits related to stock option exercises	(1,514)	(392)
Changes in assets and liabilities
Receivables	416	402
Inventories	(7,235)	2,200
Prepaid expenses	(734)	(827)
Accounts payable	4,048	(12,490)
Accrued expenses	1,421	1,194
Income taxes	11,493	46,649
Other, net	(620)	(82)
Net cash provided by operations	158,638	188,902
Cash flows from investing:
Purchase of property and equipment	(160,121)	(114,262)
Payments for acquisition of stores, net of cash acquired	(3,307)	(37,726)
Proceeds from sale of property and equipment	1,047	425
Net cash used in investing activities	(162,381)	(151,563)
Cash flows from financing:
Payments of long-term debt	(5,368)	(728)
Net borrowings of short-term debt		(600)
Proceeds from exercise of stock options	3,645	1,641
Payments of cash dividends	(12,640)	(11,416)
Excess tax benefits related to stock option exercises	1,514	392
Net cash used in financing activities	(12,849)	(10,711)
Net (decrease) increase in cash and cash equivalents	(16,592)	26,628
Cash and cash equivalents at beginning of period	55,919	59,572
Cash and cash equivalents at end of period	39,327	86,200
SUPPLEMENTAL DISCLOSURES OF CASH FLOWS INFORMATION
Interest, net of amount capitalized	17,667	17,864
Income taxes	$ 11,988	$ (27,852)