Segments and Other Geographic Reporting Segment Reporting (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2020 USD ($)	Jan. 31, 2019 USD ($)	Jan. 31, 2020 USD ($)	Jan. 31, 2019 USD ($)	Jul. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of Operating Segments			2
Number of Reportable Segments			2
Service revenues and vehicle sales:	$ 575,140	$ 484,898	$ 1,129,564	$ 946,266
Yard operations	257,351	215,460	498,142	423,154
Cost of vehicle sales	57,900	61,212	116,664	118,968
General and administrative	49,997	43,487	99,475	87,965
Operating income	209,892	164,739	415,283	316,179
Depreciation and amortization	24,282	20,399	47,296	42,268
Capital expenditures, including acquisitions	268,559	74,391	400,352	136,727
Total assets	3,048,605		3,048,605		$ 2,547,617
Goodwill	338,262		338,262		333,321
Operating Segments | United States | United States
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	482,737	390,072	946,901	761,281
Yard operations	219,278	181,335	424,108	358,977
Cost of vehicle sales	33,887	26,883	64,959	52,826
General and administrative	39,487	36,452	78,699	73,784
Operating income	190,085	145,402	379,135	275,694
Depreciation and amortization	21,698	17,877	42,265	37,269
Capital expenditures, including acquisitions	261,157	66,901	374,423	102,154
Total assets	2,526,943		2,526,943		2,094,592
Goodwill	256,998		256,998		256,998
Operating Segments | International | International
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	92,403	94,826	182,663	184,985
Yard operations	38,073	34,125	74,034	64,177
Cost of vehicle sales	24,013	34,329	51,705	66,142
General and administrative	10,510	7,035	20,776	14,181
Operating income	19,807	19,337	36,148	40,485
Depreciation and amortization	2,584	2,522	5,031	4,999
Capital expenditures, including acquisitions	7,402	7,490	25,929	34,573
Total assets	521,662		521,662		453,025
Goodwill	81,264		81,264		$ 76,323
Service revenues
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	510,034	416,807	997,890	811,613
Service revenues | Operating Segments | United States | United States
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	447,345	362,023	878,148	705,596
Service revenues | Operating Segments | International | International
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	62,689	54,784	119,742	106,017
Vehicle sales
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	65,106	68,091	131,674	134,653
Vehicle sales | Operating Segments | United States | United States
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	35,392	28,049	68,753	55,685
Vehicle sales | Operating Segments | International | International
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	$ 29,714	$ 40,042	$ 62,921	$ 78,968