Provision for Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Income Tax [Line Items]
Maximum percentage of tax benefits realized upon ultimate settlement	50.00%
Decreases in unrecognized tax benefits resulting from effective settlement	$ 1,642
Income tax benefit related to gross uncertain tax benefit releases, net	1,008
Interest and penalties related to uncertain tax benefits	295
Effective income tax rate	33.10%	34.90%
Expected decrease in unrecognized tax benefits due to resolution of uncertain tax positions	3,920
Expected decrease in interest and penalties due to resolution of uncertain tax positions	1,050
Minimum
Income Tax [Line Items]
Expected gross unrecognized tax benefits decrease	3,400
Expected decrease in interest and penalties	800
Maximum
Income Tax [Line Items]
Expected gross unrecognized tax benefits decrease	7,200
Expected decrease in interest and penalties	$ 2,300