CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (297,161)	$ (379,638)	$ (108,233)
Other comprehensive income (loss), net of tax:
Change in unrealized gain (loss) on available-for-sale securities, net of tax	(896)	(94)	2
Comprehensive loss	$ (298,057)	$ (379,732)	$ (108,231)