Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) income	$ (74,237)	$ 12,127	$ 33,481
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment, net of tax	1,375	(2,293)	(12,564)
Unrecognized gain (loss) on pension benefits, net of tax	1,279	(1,848)	630
Unrealized gain (loss) on foreign currency forward contracts, net of tax	680	187	(377)
Unrealized (loss) on available-for-sale securities, net of tax	(13)
Total other comprehensive income (loss), net of tax	3,321	(3,954)	(12,311)
Total comprehensive (loss) income	$ (70,916)	$ 8,173	$ 21,170