Contingent Liabilities, Commitments and Legal Matters - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Apr. 30, 2019	Jul. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Standby repurchase obligations amount	$ 3,337,543	$ 2,748,465
Term of commitments	up to eighteen months
Repurchase and guarantee reserve balances	$ 10,300	$ 7,400