Components of Total Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 12,671	$ 13,269	$ 13,156	$ 20,813
Reduction to unrecognized tax benefits for tax credit carry forward	(1,882)	(2,255)
Accrued interest and penalties	1,209	1,547
Total unrecognized tax benefits	11,998	12,561
Short-term, included in "Income and other taxes"	1,735	2,586
Long-term	10,263	9,975
Total unrecognized tax benefits	$ 11,998	$ 12,561