Share-based payments (Details) (USD $)	12 Months Ended								12 Months Ended						1 Months Ended		12 Months Ended
	Jan. 31, 2014	Feb. 01, 2013	Feb. 03, 2012	Jan. 31, 2014 Options	Feb. 01, 2013 Options	Feb. 03, 2012 Options	Feb. 03, 2012 Equity Appreciation Rights	Jan. 31, 2014 Equity Appreciation Rights	Jan. 31, 2014 Restricted Stock Units	Feb. 01, 2013 Restricted Stock Units	Feb. 03, 2012 Restricted Stock Units	Jan. 31, 2014 Performance Share Units	Feb. 01, 2013 Performance Share Units	Feb. 03, 2012 Performance Share Units	Apr. 06, 2012 Performance based restricted stock awards Chairman and chief executive officer	Jan. 31, 2014 2007 Stock incentive plan	Jan. 31, 2014 2007 Stock incentive plan Options Time Options	Feb. 01, 2013 2007 Stock incentive plan Options Time Options	Feb. 03, 2012 2007 Stock incentive plan Options Time Options	Jan. 31, 2014 2007 Stock incentive plan Options Performance Options	Feb. 01, 2013 2007 Stock incentive plan Options Performance Options	Feb. 03, 2012 2007 Stock incentive plan Options Performance Options	Jan. 31, 2014 2007 Stock incentive plan Options Time Options and Performance Options	Jan. 31, 2014 2007 Stock incentive plan Options Other stock option	Feb. 01, 2013 2007 Stock incentive plan Options Other stock option	Feb. 03, 2012 2007 Stock incentive plan Options Other stock option	Jan. 31, 2014 2007 Stock incentive plan Options Other stock option Board of directors	Jan. 31, 2014 2007 Stock incentive plan Options Other stock option Employee	Jan. 31, 2014 2007 Stock incentive plan Restricted Stock Units and Performance Stock Units
Share-based payments
Number of shares of common stock authorized for grant																31,142,858
Shares available for future grants																19,871,333
Vesting period																							5 years				3 years	4 years	3 years
Grant date fair value of awards issued (in dollars per share)									$ 48.20	$ 45.33	$ 33.16	$ 48.11	$ 45.25		$ 45.25
Weighted average for key assumptions used in determining the fair value
Expected dividend yield (as a percent)				0.00%	0.00%	0.00%
Expected stock price volatility (as a percent)				26.20%	26.80%	38.70%
Weighted average risk-free interest rate (as a percent)				1.20%	1.50%	2.30%
Expected term of options				6 years 3 months 18 days	6 years 3 months 18 days	6 years 9 months 18 days
Contractual term of options																							10 years
Options Issued
Balance at the beginning of the period (in shares)																	1,350,642			1,264,826				1,211,771
Granted (in shares)																								875,269
Exercised (in shares)																	(871,037)			(868,441)				(53,813)
Canceled (in shares)																	(15,042)			(20,076)				(192,685)
Balance, at the end of the period (in shares)																	464,563	1,350,642		376,309	1,264,826			1,840,542	1,211,771
Exercisable at the end of the period (in shares)																	292,807			336,716				369,424
Average Exercise Price
Balance at the beginning of the period (in dollars per share)																	$ 13.69			$ 13.96				$ 42.77
Granted (in dollars per share)																								$ 48.80
Exercised (in dollars per share)																	$ 11.11			$ 11.28				$ 41.51
Canceled (in dollars per share)																	$ 25.17			$ 22.69				$ 46.69
Balance at the end of the period (in dollars per share)																	$ 18.15	$ 13.69		$ 19.68	$ 13.96			$ 45.26	$ 42.77
Exercisable at the end of the period (in dollars per share)																	$ 15.43			$ 18.56				$ 38.51
Remaining Contractual Term
Balance, at the end of the period																	5 years 7 months 6 days			5 years 9 months 18 days				8 years 6 months
Exercisable at the end of the period																	5 years 3 months 18 days			5 years 8 months 12 days				7 years 4 months 24 days
Intrinsic Value
Balance at the end of the period																	$ 17,730,000			$ 13,790,000				$ 20,356,000
Balance at the end of the period									34,723,000			8,978,000
Exercisable at the end of the period																	11,973,000			12,714,000				6,580,000
Weighted average grant date fair value (in dollars per share)																			$ 13.47			$ 13.47		$ 13.86	$ 13.54	$ 13.14
Intrinsic value of options exercised																	39,400,000	117,300,000	41,400,000	39,100,000	106,400,000	41,800,000		800,000	300,000	1,600,000
Units Issued
Awards outstanding at the beginning of the period (in shares or rights)								0	288,927			162,688
Granted (in shares or rights)							818,847		509,440			72,846		0	326,037
Vested (in shares or rights)							(768,561)		(98,063)			(54,973)
Canceled (in shares or rights)							(50,286)		(83,777)			(21,142)
Awards outstanding at the end of the period (in shares or rights)								0	616,527	288,927		159,419	162,688
Share-based compensation expense
Pre-tax	20,961,000	21,664,000	23,981,000	7,634,000	14,078,000	15,121,000	8,731,000		9,879,000	3,504,000	129,000	3,448,000	4,082,000
Net of tax	12,765,000	13,200,000	14,604,000	4,649,000	8,578,000	9,208,000	5,317,000		6,016,000	2,135,000	79,000	2,100,000	2,487,000
Total unrecognized compensation cost	$ 53,500,000
Expected weighted average expense recognition period (in years)	1 year 6 months