Quarterly Financial Data (Schedule Of Quarterly Financial Data) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Apr. 30, 2012		Jan. 31, 2012		Oct. 31, 2011		Jul. 31, 2011		Apr. 30, 2011		Jan. 31, 2011		Oct. 31, 2010		Jul. 31, 2010		Apr. 30, 2012		Apr. 30, 2011		Apr. 30, 2010
Quarterly Data [Line Items]
Revenue	$ 1,752,504		$ 1,578,950		$ 1,782,518		$ 1,873,832		$ 1,549,495		$ 1,374,199		$ 1,349,519		$ 1,362,027		$ 6,987,804		$ 5,635,240
Gross profit	245,240	[1]	228,750	[1]	262,918	[1]	266,782	[1]	217,188	[1]	202,531	[1]	227,377	[1]	233,971	[1]	1,003,690	[1]	881,067	[1]	792,352
Net earnings	23,069		16,699		37,632		39,391		22,770		12,875		21,692		37,286		116,791		94,623		116,962
Basic	$ 0.61		$ 0.44		$ 0.99		$ 1.04		$ 0.60		$ 0.34		$ 0.51		$ 0.73		$ 3.07		$ 2.24		$ 2.30
Diluted	$ 0.60		$ 0.43		$ 0.98		$ 1.03		$ 0.60		$ 0.34		$ 0.51		$ 0.73		$ 3.04		$ 2.22		$ 2.29
Gasoline [Member]
Quarterly Data [Line Items]
Revenue	1,284,669		1,141,230		1,288,498		1,377,914		1,143,288		991,143		927,617		936,654		5,092,311		3,998,702
Gross profit	49,371	[1]	49,180	[1]	62,688	[1]	65,320	[1]	52,276	[1]	48,101	[1]	52,755	[1]	58,906	[1]	226,559	[1]	212,038	[1]
Grocery And Other Merchandise [Member]
Quarterly Data [Line Items]
Revenue	330,809		311,199		357,816		365,171		293,432		276,075		308,900		317,206		1,364,995		1,195,613
Gross profit	109,196	[1]	99,099	[1]	116,221	[1]	118,729	[1]	94,185	[1]	85,385	[1]	101,655	[1]	104,025	[1]	443,245	[1]	385,250	[1]
Prepared Food & Fountain [Member]
Quarterly Data [Line Items]
Revenue	128,281		118,750		128,838		123,843		105,486		100,189		107,183		102,382		499,712		415,240
Gross profit	77,944	[1]	72,714	[1]	76,658	[1]	75,843	[1]	63,454	[1]	62,266	[1]	67,161	[1]	65,270	[1]	303,159	[1]	258,151	[1]
Other Revenue [Member]
Quarterly Data [Line Items]
Revenue	8,745		7,771		7,366		6,904		7,289		6,792		5,819		5,785		30,786		25,685
Gross profit	$ 8,729	[1]	$ 7,757	[1]	$ 7,351	[1]	$ 6,890	[1]	$ 7,273	[1]	$ 6,779	[1]	$ 5,806	[1]	$ 5,770	[1]	$ 30,727	[1]	$ 25,628	[1]

[1] Gross profit is given before charge for depreciation and amortization and credit card fees.