CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (209,813)	$ (85,674)	$ (426,841)	$ (209,792)
Other comprehensive loss, net of tax:
Change in unrealized (loss) gain on available-for-sale securities, net of tax	478	(517)	1,331	(1,131)
Comprehensive loss	$ (209,335)	$ (86,191)	$ (425,510)	$ (210,923)