Provision for Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016	Jul. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate	34.10%	31.30%	33.00%	33.10%
New accounting pronouncement or change in accounting principle, effect of change on net income	$ 0		$ 1,843
Interest and penalties related to uncertain tax benefits	95				$ 191
Decreases in unrecognized tax benefits resulting from effective settlement	264		1,156
Income tax benefit related to gross uncertain tax benefit releases, net	170		750
Expected decrease in unrecognized tax benefits due to resolution of uncertain tax positions	$ 5,448		5,448
Expected decrease in interest due to resolution of uncertain tax positions			$ 905