Contingent Liabilities, Commitments and Legal Matters - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2016	Jul. 31, 2016
Loss Contingencies [Line Items]
Standby Repurchase Obligations Amount	$ 1,919,329	$ 1,898,307
Term of Commitments	Up to eighteen months
Repurchase and guarantee reserve balances	$ 5,834	$ 6,068