Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 7,110	$ (59,664)	$ 19,317	$ (49,618)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment, net of tax	(1,703)	178	3,038	(2,415)
Unrecognized gain on pension benefits, net of tax	41	58	114	167
Unrealized (loss) on foreign currency forward contracts, net of tax	(466)	(324)	(571)	(153)
Unrealized (loss) on available-for-sale securities, net of tax	(33)		(150)
Total other comprehensive (loss) income, net of tax	(2,161)	(88)	2,431	(2,401)
Total comprehensive income (loss)	$ 4,949	$ (59,752)	$ 21,748	$ (52,019)