Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2011	Oct. 31, 2010
Cash flows from operations:
Net earnings	$ 77,023	$ 58,978
Adjustments to reconcile net earnings to net cash provided by operations:
Depreciation and amortization	46,327	39,604
Other amortization	389	275
Stock based compensation	1,521	1,057
Loss on sale and disposal of property and equipment	848	111
Deferred income taxes	26,140	15,651
Excess tax benefits related to stock option exercises	(392)	(490)
Loss on early retirement of debt		11,350
Changes in assets and liabilities:
Receivables	402	(3,218)
Inventories	2,200	3,365
Prepaid expenses	(827)	(610)
Accounts payable	(12,490)	28,898
Accrued expenses	1,194	9,068
Income taxes	46,649	1,602
Other, net	(82)	(18)
Net cash provided by operations	188,902	165,623
Cash flows from investing:
Purchase of property and equipment	(114,262)	(87,888)
Payments for acquisition of stores, net of cash acquired	(37,726)	(27,354)
Proceeds from sale of property and equipment	425	780
Net cash used in investing activities	(151,563)	(114,462)
Cash flows from financing:
Proceeds from long-term debt		569,000
Payments of long-term debt	(728)	(64,586)
Net borrowing of short-term debt	(600)
Proceeds from exercise of stock options	1,641	3,120
Payments of cash dividends	(11,416)	(10,218)
Repurchase of common stock		(501,026)
Payments of prepayment penalties		(11,350)
Excess tax benefits related to stock option exercises	392	490
Net cash used in financing activities	(10,711)	(14,570)
Net increase in cash and cash equivalents	26,628	36,591
Cash and cash equivalents at beginning of the period	59,572	151,676
Cash and cash equivalents at end of the period	86,200	188,267
SUPPLEMENTAL DISCLOSURES OF CASH FLOWS INFORMATION
Interest, net of amount capitalized	17,864	5,450
Income taxes	$ (27,852)	$ 17,372