Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2012	Jul. 31, 2011
Cash flows from operations:
Net income	$ 39,031	$ 39,391
Adjustments to reconcile net income to net cash provided by operations
Depreciation and amortization	26,536	22,895
Other amortization	75	385
Stock based compensation	1,036	477
Loss on sale and disposal of property and equipment	1,584	386
Deferred income taxes	4,737	9,634
Excess tax benefits related to stock option exercises	(1,481)	(268)
Changes in assets and liabilities
Receivables	446	(2,183)
Inventories	(7,752)	(2,243)
Prepaid expenses	(1,339)	(1,259)
Accounts payable	8,779	30,133
Accrued expenses	13,607	15,189
Income taxes	21,911	50,318
Other, net	(639)	4
Net cash provided by operations	106,531	162,859
Cash flows from investing:
Purchase of property and equipment	(71,776)	(47,514)
Payments for acquisition of stores, net of cash acquired		(31,115)
Proceeds from sale of property and equipment	507	322
Net cash used in investing activities	(71,269)	(78,307)
Cash flows from financing:
Payments of long-term debt	(182)	(384)
Net borrowings of short-term debt		(600)
Proceeds from exercise of stock options	3,476	1,316
Payments of cash dividends	(6,320)	(5,707)
Excess tax benefits related to stock option exercises	1,481	268
Net cash used in financing activities	(1,545)	(5,107)
Net increase in cash and cash equivalents	33,717	79,445
Cash and cash equivalents at beginning of period	55,919	59,572
Cash and cash equivalents at end of period	89,636	139,017
SUPPLEMENTAL DISCLOSURES OF CASH FLOWS INFORMATION
Interest, net of amount capitalized	99	126
Income taxes	$ (3,556)	$ (36,035)