Condensed Consolidated Statement of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (48,622)	$ (1,819)	$ (103,091)	$ (5,703)
Foreign currency translation adjustments	(1,522)	183	(94)	(654)
Unrealized gains (losses) on available-for-sale securities, net of tax benefit of $134 and $4 for the three months ended October 31, 2016 and 2015, respectively	(198)	49	(623)	(352)
Reclassification adjustment for realized losses (gains) included in net loss	(100)	(60)	(85)	(119)
Other comprehensive loss	(1,820)	172	(802)	(1,125)
Comprehensive loss	$ (50,442)	$ (1,647)	$ (103,893)	$ (6,828)