Stock Repurchase Activity (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 19, 2015	Oct. 31, 2015	Nov. 01, 2014	Oct. 31, 2015	Nov. 01, 2014	Jan. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Shares of common stock repurchased to date (in shares)		15,732,926		15,732,926		13,595,537
Value of common stock repurchased to date		$ 492,278,000		$ 492,278,000		$ 404,334,000
Under November 2012 Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Amount authorized under stock repurchase program		$ 250,000,000		$ 250,000,000
Stock Repurchase Program Expiration Date	Nov. 19, 2015
Shares of common stock repurchased during the period (in shares)		1,341,170	371,589	2,137,389	1,072,295
Shares acquired from holders of restricted stock unit awards to satisfy tax withholding requirements (in shares)		0	689	42,877	81,895
Value of common stock repurchased during current period		$ 50,500,000	$ 16,700,000	$ 87,900,000	$ 54,600,000
Value of tax withholding payments related to shares acquired from holders of restricted stock unit awards		0	$ 31,000.0	2,100,000	$ 4,700,000
Value of shares of common stock remaining available for repurchase under the program		$ 87,500,000		$ 87,500,000
Under November 2015 Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Amount authorized under stock repurchase program	$ 300,000,000
Stock Repurchase Program Expiration Date	Feb. 02, 2019