Provision for Income Taxes - Additional information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012
Income Taxes [Line Items]
Maximum percentage of tax benefits realized upon ultimate settlement			50.00%
Interest and penalties related to uncertain tax benefits	$ 210		$ 907
Accrued an additional uncertain tax benefit related to prior tax periods	118		340
Decreases in unrecognized tax benefits resulting from effective settlement	3,916		8,730
Income tax benefit related to gross uncertain tax benefit releases, net	2,593		4,407
Effective income tax rate	30.10%	32.50%	30.30%	34.10%
Anticipated decrease in unrecognized tax benefits			3,300
Accrued interest and penalties related to unrecognized tax benefits	750		750
Minimum
Income Taxes [Line Items]
Anticipated decrease in unrecognized tax benefits possible range			1,100
Accrued interest and penalties related to unrecognized tax benefits possible range	600		600
Maximum
Income Taxes [Line Items]
Anticipated decrease in unrecognized tax benefits possible range			6,900
Accrued interest and penalties related to unrecognized tax benefits possible range	$ 2,700		$ 2,700