Segments and Other Geographic Reporting Segment Reporting (Details) $ in Thousands	3 Months Ended
	Oct. 31, 2018 USD ($)	Oct. 31, 2017 USD ($)	Jul. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of Operating Segments	2
Number of Reportable Segments	2
Service revenues and vehicle sales:	$ 461,368	$ 419,168
Yard operations	207,694	217,607
Cost of vehicle sales	57,756	38,297
General and administrative	44,478	39,322
Operating income	151,440	123,942
Interest (expense) income, net	(3,691)	(5,398)
Other (expense) income, net	1,037	(4,416)
Intercompany income (expense)	0	0
Income before income taxes	148,786	114,128
Income taxes	34,703	36,568
Net income (Loss), Including Portion Attributable to Noncontrolling Interest	114,083	77,560
Depreciation and amortization	21,869	15,902
Capital expenditures, including acquisitions	62,336	41,361
Total assets	2,381,788		$ 2,307,698
Goodwill	335,120		337,235
Net Income (Loss) Attributable to Parent	114,083	77,515
Operating Segments | United States
Segment Reporting Information [Line Items]
Cost of vehicle sales	25,943	18,760
Operating Segments | International
Segment Reporting Information [Line Items]
Cost of vehicle sales	31,813	19,537
Operating Segments | United States | United States
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	371,209	351,105
Yard operations	177,642	192,833
General and administrative	37,332	33,493
Operating income	130,292	106,019
Interest (expense) income, net	(3,814)	(5,488)
Other (expense) income, net	625	(4,111)
Intercompany income (expense)	1,411	2,304
Income before income taxes	128,514	98,724
Income taxes	30,466	33,585
Net income (Loss), Including Portion Attributable to Noncontrolling Interest	98,048	65,139
Depreciation and amortization	19,392	13,529
Capital expenditures, including acquisitions	35,253	38,905
Total assets	1,934,693		1,856,058
Goodwill	256,434		256,434
Operating Segments | International | International
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	90,159	68,063
Yard operations	30,052	24,774
General and administrative	7,146	5,829
Operating income	21,148	17,923
Interest (expense) income, net	123	90
Other (expense) income, net	412	(305)
Intercompany income (expense)	(1,411)	(2,304)
Income before income taxes	20,272	15,404
Income taxes	4,237	2,983
Net income (Loss), Including Portion Attributable to Noncontrolling Interest	16,035	12,421
Depreciation and amortization	2,477	2,373
Capital expenditures, including acquisitions	27,083	2,456
Total assets	447,095		451,640
Goodwill	78,686		$ 80,801
Service revenues
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	394,806	374,125
Service revenues | Operating Segments | United States | United States
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	343,573	331,391
Service revenues | Operating Segments | International | International
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	51,233	42,734
Vehicle sales
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	66,562	45,043
Vehicle sales | Operating Segments | United States | United States
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	27,636	19,714
Vehicle sales | Operating Segments | International | International
Segment Reporting Information [Line Items]
Service revenues and vehicle sales:	$ 38,926	$ 25,329