Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2021	Oct. 31, 2020
Disaggregation of Revenue [Line Items]
Service revenues and vehicle sales	$ 810,132	$ 592,940
Service revenues
Disaggregation of Revenue [Line Items]
Service revenues and vehicle sales	667,818	515,372
Vehicle sales
Disaggregation of Revenue [Line Items]
Service revenues and vehicle sales	$ 142,314	$ 77,568