Related party transactions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Feb. 01, 2013
Related party transactions
Number of seats on Board of Directors held by KKR and Goldman Sachs & Co.	0	3
KKR | Credit facilities all
Related party transactions
Payment of financing costs	$ 0.7	$ 1.6
Goldman, Sachs & Co. and affiliates | Credit facilities all
Related party transactions
Payment of financing costs	$ 2.2	$ 1.7