Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (20,190)	$ (14,991)
Foreign currency translation adjustments	(694)	133
Unrealized gains (losses) on available-for-sale securities	(1,839)	1,331
Tax benefit (expense) on unrealized gains (losses) on available-for-sale securities	359	(328)
Reclassification adjustment for realized gains (losses) included in net income (loss)	347	46
Total other comprehensive income (loss)	(1,827)	1,182
Comprehensive income (loss)	$ (22,017)	$ (13,809)