Quarterly Financial Data - Schedule of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Total revenue
Total revenue	$ 1,846,460	$ 1,769,993	$ 1,920,055	$ 1,970,079	$ 1,582,954	$ 1,565,940	$ 1,924,600	$ 2,048,592	$ 7,506,587	$ 7,122,086	$ 7,767,216
Gross profit
Gross profit	398,219	389,629	443,518	449,795	388,220	371,169	442,990	411,242	1,681,161	1,613,621	1,439,785
Net income	$ 30,078	$ 22,835	$ 57,180	$ 67,392	$ 47,044	$ 38,099	$ 79,033	$ 61,806	$ 177,485	$ 225,982	$ 180,628
Net income per common share
Basic (in Dollars per share)	$ 0.77	$ 0.58	$ 1.46	$ 1.72	$ 1.20	$ 0.98	$ 2.03	$ 1.59	$ 4.54	$ 5.79	$ 4.66
Diluted (in Dollars per share)	$ 0.76	$ 0.58	$ 1.44	$ 1.70	$ 1.19	$ 0.97	$ 2.00	$ 1.57	$ 4.48	$ 5.73	$ 4.62
Fuel
Total revenue
Total revenue	$ 1,099,743	$ 1,053,990	$ 1,113,351	$ 1,147,044	$ 873,081	$ 888,744	$ 1,166,736	$ 1,286,241	$ 4,414,128	$ 4,214,802
Gross profit
Gross profit	85,592	89,265	99,060	104,429	85,828	85,460	122,690	87,681	378,347	381,659
Grocery & other merchandise
Total revenue
Total revenue	500,068	476,309	544,799	566,174	477,487	453,388	516,578	526,620	2,087,349	1,974,073
Gross profit
Gross profit	155,374	148,099	174,590	179,127	153,299	141,482	162,904	171,549	657,190	629,234
Prepared food & fountain
Total revenue
Total revenue	233,150	228,278	248,345	243,655	218,349	209,595	229,388	223,381	953,430	880,713
Gross profit
Gross profit	143,774	140,869	156,329	153,052	135,073	130,027	145,513	139,679	594,024	550,292
Other
Total revenue
Total revenue	13,499	11,416	13,560	13,206	14,037	14,213	11,898	12,350	51,680	52,498
Gross profit
Gross profit	$ 13,479	$ 11,396	$ 13,539	$ 13,187	$ 14,020	$ 14,200	$ 11,883	$ 12,333	$ 51,600	$ 52,436