Related party transactions (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Aug. 03, 2012	Jul. 29, 2011
Affiliates of KKR and Goldman, Sachs & Co. | Term loan facility
Related party transactions
Interest paid	$ 32.1	$ 36.8
Affiliates of KKR and Goldman, Sachs & Co. | ABL Facility, as amended and restated
Related party transactions
Interest paid	2.6	0
Affiliates of KKR and Goldman, Sachs & Co. | Senior notes
Related party transactions
Payments of financing costs	2.3
Goldman, Sachs & Co. and affiliates
Related party transactions
Interest rate swap payment	2.5	10.6
Goldman, Sachs & Co. and affiliates | Term loan facility
Related party transactions
Payments of financing costs	0.4
Goldman, Sachs & Co. and affiliates | ABL Facility, as amended and restated
Related party transactions
Payments of financing costs	0.1
KKR
Related party transactions
Number of members serving on the entity's board of directors	2
KKR | Term loan facility
Related party transactions
Payments of financing costs	$ 0.4