Losses Due to Repurchases Related to Repurchase Agreements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Loss Contingencies [Line Items]
Cost of units repurchased	$ 4,650	$ 7,171	$ 1,386
Realization of units resold	3,832	5,906	1,098
Losses due to repurchase	$ 818	$ 1,265	$ 288