Losses Due to Repurchases Related to Repurchase Agreements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Loss Contingencies [Line Items]
Cost of units repurchased	$ 7,171	$ 1,386	$ 6,926
Realization of units resold	5,906	1,098	6,020
Losses due to repurchase	$ 1,265	$ 288	$ 906