Stockholders' Equity (Details Textual) (USD $)	1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended					1 Months Ended	12 Months Ended
	Mar. 31, 2012	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011	Jul. 31, 2008 Employee Stock [Member]	Jan. 31, 2011 Employee Stock [Member]	Jan. 31, 2013 Employees [Member]	Jan. 31, 2012 Employees [Member]	Jan. 31, 2011 Employees [Member]	Jan. 31, 2011 Compensation and Incentive Plan 2011 [Member]	May 31, 2012 Compensation and Incentive Plan 2011 [Member] Executive Officer [Member]	Jan. 31, 2013 Amended and Restated Equity Compensation and Incentive Plan 2005 [Member]	Jan. 31, 2013 Restricted Stock Units (Rsus) [Member]	Jan. 31, 2011 Restricted Stock Units (Rsus) [Member]	Jan. 31, 2013 Restricted Stock Units (Rsus) [Member] Executive Officer [Member] Performance Based Plan [Member]
Preferred Stock, Shares Authorized		5,000,000
Stock Issued During Period, Shares, New Issues										2,800,000		2,800,000
Stock Repurchase Program, Authorized Amount	$ 25,000,000
Stock Repurchase Program Shares Authorized To Repurchase Par Value	$ 0.01
Stock Repurchased During Period, Shares (in shares)		764,024
Stock Repurchase Price Per Share (in dollars per share)		$ 8.12
Stock Repurchased During Period, Value		6,200,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		857,515
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent				100.00%
Share Based Compensation Arrangement By Share Based Payment Award, Vesting Period Description										Awards granted under the 2011 Plan generally vest over three years and expire 10 years from the date of the grant
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 3.78	$ 2.86	$ 3.70
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized		2,300,000											3,900,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value		500,000	800,000	500,000
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options						700,000	2,200,000	1,800,000	2,100,000
Share Based Compensation Arrangement By Share Based Payment Award Estimated Weighted Average Amortization Period													2 years 1 month 6 days
Share Based Compensation Arrangement By Share Based Payment Award Unvested Stock Cancelled In Period Grant Date Fair Value														1,900,000
Stock-based compensation expense		$ 4,101,000	$ 2,988,000	$ 2,598,000										$ 1,300,000
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee					2,200,000
Share Based Compensation Arrangement By Share Based Payment Award, Purchase Price Description					The purchase price of the stock was 85% of the lesser of the average market price of the common stock on the first or last business day of each six-month plan period.
Issuance of common stock in connection with the employee stock purchase plan (in shares)						135,632
Shares, Granted		892,500	250,000	15,000							875,000				90,673