Quarterly Financial Data - Schedule of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Total revenue
Total revenue	$ 2,089,037	$ 2,054,603	$ 2,153,745	$ 2,093,739	$ 1,846,460	$ 1,769,993	$ 1,920,055	$ 1,970,079	$ 8,391,124	$ 7,506,587	$ 7,122,086
Gross profit
Gross profit	405,115	419,924	467,657	476,697	398,219	389,629	443,518	449,795	1,769,393	1,681,161
Net income	$ 19,262	$ 192,965	$ 48,918	$ 56,758	$ 30,078	$ 22,835	$ 57,180	$ 67,392	$ 317,903	$ 177,485	$ 225,982
Net income per common share
Basic (in Dollars per share)	$ 0.52	$ 5.13	$ 1.29	$ 1.48	$ 0.77	$ 0.58	$ 1.46	$ 1.72	$ 8.41	$ 4.54	$ 5.79
Diluted (in Dollars per share)	$ 0.51	$ 5.08	$ 1.28	$ 1.46	$ 0.76	$ 0.58	$ 1.44	$ 1.70	$ 8.34	$ 4.48	$ 5.73
Fuel
Total revenue
Total revenue	$ 1,321,417	$ 1,297,340	$ 1,306,246	$ 1,220,985	$ 1,099,743	$ 1,053,990	$ 1,113,351	$ 1,147,044	$ 5,145,988	$ 4,414,128
Gross profit
Gross profit	86,640	100,272	110,686	109,212	85,592	89,265	99,060	104,429	406,811	378,347
Grocery & other merchandise
Total revenue
Total revenue	511,834	502,750	572,151	597,413	500,068	476,309	544,799	566,174	2,184,147	2,087,349
Gross profit
Gross profit	159,929	160,150	183,133	190,364	155,374	148,099	174,590	179,127	693,576	657,190
Prepared food & fountain
Total revenue
Total revenue	241,163	240,618	261,998	261,840	233,150	228,278	248,345	243,655	1,005,621	953,430
Gross profit
Gross profit	143,949	145,632	160,510	163,645	143,774	140,869	156,329	153,052	613,736	594,024
Other
Total revenue
Total revenue	14,623	13,895	13,350	13,501	13,499	11,416	13,560	13,206	55,368	51,680
Gross profit
Gross profit	$ 14,597	$ 13,870	$ 13,328	$ 13,476	$ 13,479	$ 11,396	$ 13,539	$ 13,187	$ 55,270	$ 51,600