Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended			12 Months Ended
	Jan. 20, 2012	Aug. 15, 2011	Dec. 31, 2009	Jul. 31, 2012 Year	Jul. 31, 2011	Jul. 31, 2010	Jan. 18, 2012	Aug. 12, 2011
Stockholders Equity [Line Items]
Shares purchased, shares			3,980,000
Shares purchased, price per share			$ 29.00
Shares purchased, value			$ 115,420	$ 77,000		$ 115,420
Percentage of common stock outstanding at time of repurchase			7.20%
Stock repurchase agreement, number of shares agreed to be repurchased	1,000,000	1,000,000
Stock repurchase agreement, entry date	Jan. 18, 2012	Aug. 12, 2011
Stock repurchase agreement, price per share	$ 28.50	$ 20.00
Stock repurchase agreement, aggregate purchase price	28,500	20,000
Closing price of common stock							$ 29.34	$ 20.62
Percentage of issued and outstanding common stock prior to the repurchase	1.80%	1.80%
Number of shares allowed for granting under restricted stock plan				600,000
Option expiration from the date of grant, in years				10 years
Weighted average remaining contractual life of outstanding options, years				6.33
Weighted average remaining contractual life of exercisable options, years				5.68
Weighted average fair value of options granted					$ 10.80	$ 14.69
Total compensation expenses				0	0	12
Cash received from stock option exercises				1,428	1,047	16
Total intrinsic value of stock options exercised				931	1,551	3
Tax benefits from stock compensation expense				224	1,172	481
Stock awards restriction expiration of 50 %, years after date of issue				5
Stock awards restriction expiration of remaining balance, years after date of issue				6
Restricted stock expiration, percentage				50.00%
Minimum
Stockholders Equity [Line Items]
Option vesting period				3 years
Maximum
Stockholders Equity [Line Items]
Option vesting period				5 years
2010 Equity Incentive Plan
Stockholders Equity [Line Items]
Number of shares authorized under stock option plan				2,000,000
Number of shares allowed for granting under restricted stock plan				1,859,959
2006 Equity Incentive Plan
Stockholders Equity [Line Items]
Number of shares authorized under stock option plan				1,100,000
Number of shares allowed for granting under restricted stock plan				30,000
Stock Option Awards
Stockholders Equity [Line Items]
Total compensation expenses				645	2,707	1,375
Unrecognized compensation costs				1,786
Weighted average recognition period for compensation expenses, years				3.16
Restricted Stock Awards
Stockholders Equity [Line Items]
Total compensation expenses				43	0	0
Unrecognized compensation costs				560
Weighted average recognition period for compensation expenses, years				4.88
Restricted stock awards vesting period				5 years
Catterton Repurchase Agreements
Stockholders Equity [Line Items]
Stock repurchase agreement, number of shares agreed to be repurchased	1,000,000
Stock repurchase agreement, entry date	Jan. 18, 2012
Stock repurchase agreement, price per share	$ 28.50
Stock repurchase agreement, aggregate purchase price	$ 28,500
Closing price of common stock							$ 29.34
Percentage of issued and outstanding common stock prior to the repurchase	1.80%