Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	Jul. 31, 2016	Jul. 31, 2015
Payables and Accruals [Abstract]
Trade accounts payable	$ 30,087	$ 15,287
Accounts payable to sellers	46,866	42,230
Buyer deposits and prepayments	40,500	33,871
Accrued compensation and benefits	33,382	25,647
Accrued insurance	5,753	5,796
Other accrued liabilities	35,791	24,621
Total accounts payable and accrued expenses	$ 192,379	$ 147,452