Income taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Nov. 01, 2013	Nov. 02, 2012	Nov. 01, 2013	Nov. 02, 2012
Income taxes
Amended Tax Return Liability Refund Adjustment	$ 5.1		$ 5.1
Reserves for uncertain tax benefits	20.1		20.1
Interest accrued related to uncertain tax benefits	2.4		2.4
Penalties accrued related to uncertain tax benefits	0.4		0.4
Aggregate reserve for uncertain tax positions including interest and penalties	22.9		22.9
Reserves for uncertain tax benefits included in current liabilities as Accrued expenses and other	4.4		4.4
Reserves for uncertain tax benefits included in noncurrent Other liabilities	18.5		18.5
Reserve for uncertain tax positions for which a reduction is reasonably possible in the next twelve months	11.9		11.9
Reserve for uncertain tax positions that would impact effective tax rate if recognized	$ 20.1		$ 20.1
Effective income tax rates (as a percent)	35.60%	37.40%	36.80%	36.60%