Provision for Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
Income Tax [Line Items]
Effective income tax rate	31.40%	28.00%	31.10%	31.60%
Decreases in unrecognized tax benefits resulting from effective settlement			$ 4,506
Income tax benefit related to gross uncertain tax benefit releases, net			2,387
Accrued an additional uncertain tax benefit related to prior tax periods	90		90
Interest and penalties related to uncertain tax benefits	147		293
Expected decrease in unrecognized tax benefits due to resolution of uncertain tax positions			2,560
Expected decrease in interest and penalties due to resolution of uncertain tax positions			385
Minimum
Income Tax [Line Items]
Expected gross unrecognized tax benefits decrease			100
Expected decrease in interest and penalties			150
Maximum
Income Tax [Line Items]
Expected gross unrecognized tax benefits decrease			2,700
Expected decrease in interest and penalties			$ 1,200