Income Taxes - Reconciliation of Federal Statutory Income Tax Provision to Effective Income Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Income Tax Disclosure [Abstract]
Expected provision at U.S. federal statutory rate	$ (14,039)	$ (16,975)	$ (20,536)
State income taxes-net of federal benefit	0	2	(96)
Stock-based compensation	78	668	98
Common stock warrant	0	0	63
Tax credits	(941)	(391)	(225)
Foreign tax rate differential	(30)	(80)	(67)
Acquisition costs	0	0	125
Change in valuation allowance	15,301	17,570	20,790
Other	(154)	(367)	240
Total income tax provision	$ 215	$ 427	$ 392