Segments and Other Geographic Information (Details 1) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Jul. 31, 2017		Apr. 30, 2017	[1],[2]	Jan. 31, 2017	[1],[2]	Oct. 31, 2016	[1],[2]	Jul. 31, 2016		Apr. 30, 2016	[1]	Jan. 31, 2016	[1]	Oct. 31, 2015	[1]	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total service revenues and vehicle sales																	$ 1,447,981	$ 1,268,449	$ 1,146,079
Yard operations																	678,401	582,904	526,291
Cost of vehicle sales																	137,552	140,959	136,412
General and administrative																	151,364	138,116	138,975
Impairment of long-lived assets																	19,365	0	0
Operating income	$ 110,807	[1]	$ 136,788		$ 108,880		$ 104,824		$ 106,191	[1]	$ 121,948		$ 92,085		$ 86,246		461,299	406,470	344,401
Interest (expense) income, net																	(22,373)	(22,157)	(17,304)
Other income, net																	1,174	11,552	4,972
Intercompany income (expense)																	0	0	0
Income before income tax expense	106,379	[1]	131,088		100,099		102,534		105,985	[1]	116,568		91,552		81,760		440,100	395,865	332,069
Income tax expense																	45,839	125,505	112,286
Net income	70,335	[1]	$ 90,546		$ 66,066		$ 167,280		84,120	[1]	$ 74,623		$ 59,007		$ 52,610		394,227	270,360	219,783
Net Income (Loss) Available to Common Stockholders, Basic																	394,261
Depreciation and amortization																	57,000	48,575	46,573
Capital expenditures, including acquisitions																	332,990	173,917	79,153
Total assets	1,982,501								1,649,820								1,982,501	1,649,820	1,798,660
Goodwill	340,243								260,198								340,243	260,198	271,850
Operating segments | United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total service revenues and vehicle sales																	1,193,188	1,016,036	902,880
Yard operations																	585,587	494,146	440,517
Cost of vehicle sales																	61,484	55,866	52,232
General and administrative																	130,392	118,315	120,140
Impairment of long-lived assets																	19,365
Operating income																	396,360	347,709	289,991
Interest (expense) income, net																	(23,373)	(23,178)	(17,622)
Other income, net																	(10)	1,216	2,707
Intercompany income (expense)																	12,549	13,266	11,093
Income before income tax expense																	385,526	339,013	286,169
Income tax expense																	34,985	115,667	102,379
Net income																	350,541	223,346	183,790
Depreciation and amortization																	47,507	39,083	36,238
Capital expenditures, including acquisitions																	317,646	153,451	64,769
Total assets	1,514,018								1,249,755								1,514,018	1,249,755	1,404,946
Goodwill	259,162								179,906								259,162	179,906	176,890
Operating segments | International
Revenues from External Customers and Long-Lived Assets [Line Items]
Total service revenues and vehicle sales																	254,793	252,413	243,199
Yard operations																	92,814	88,758	85,774
Cost of vehicle sales																	76,068	85,093	84,180
General and administrative																	20,972	19,801	18,835
Impairment of long-lived assets																	0
Operating income																	64,939	58,761	54,410
Interest (expense) income, net																	1,000	1,021	318
Other income, net																	1,184	10,336	2,265
Intercompany income (expense)																	(12,549)	(13,266)	(11,093)
Income before income tax expense																	54,574	56,852	45,900
Income tax expense																	10,854	9,838	9,907
Net income																	43,720	47,014	35,993
Depreciation and amortization																	9,493	9,492	10,335
Capital expenditures, including acquisitions																	15,344	20,466	14,384
Total assets	468,483								400,065								468,483	400,065	393,714
Goodwill	$ 81,081								$ 80,292								$ 81,081	$ 80,292	$ 94,960

[1] Earnings per share were computed independently for each of the periods presented; therefore, the sum of the earnings per share amounts for the quarters may not equal the total for the year.

[2] arnings per share data were revised from previously reported amounts due to a two-for-one common stock split effected in the form of a stock dividend. See Note 1 — Summary of Significant Accounting Policies.