Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		12 Months Ended
	Oct. 31, 2012 Store	Dec. 31, 2010	Jan. 31, 2013 D	Jan. 31, 2012	Jan. 31, 2011
Accounting Policies [Line Items]
Ownership interest in joint venture			51.00%
Percentage of ownership interest sold	50.00%
Number of outlets	11
Anti-dilutive shares excluded from diluted net income per share calculation				20,000	407,850
Common stock issued in connection with exercise or vesting of equity awards			337,825	223,000	488,428
Common stock issued in connection with exercise of outstanding warrants		375,000
Restricted stock awards vesting period, minimum			4 years
Restricted stock awards vesting period, maximum			5 years
Number of consecutive trading days for stock price to trade above a predetermined market level before the award vests			20
Wholesale shipping and handling costs			$ 50.7	$ 44.9	$ 38.1
Advertising expense			54.1	43.8	36.4
Prepaid advertising			$ 5.5	$ 3.9
Minimum
Accounting Policies [Line Items]
Intangible assets, estimated useful lives			3 years
Maximum
Accounting Policies [Line Items]
Intangible assets, estimated useful lives			15 years
Stock options, vesting term			10 years