Related party transactions (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended		9 Months Ended
	Oct. 09, 2012 Credit Facilities	Nov. 02, 2012 Credit Facilities	Nov. 02, 2012 Affiliates of KKR and Goldman, Sachs & Co. Term loan facility	Oct. 28, 2011 Affiliates of KKR and Goldman, Sachs & Co. Term loan facility	Nov. 02, 2012 Affiliates of KKR and Goldman, Sachs & Co. ABL Facility	Oct. 28, 2011 Affiliates of KKR and Goldman, Sachs & Co. ABL Facility	Nov. 02, 2012 Affiliates of KKR and Goldman, Sachs & Co. Senior notes	Nov. 02, 2012 Goldman, Sachs & Co. and affiliates	Oct. 28, 2011 Goldman, Sachs & Co. and affiliates	Nov. 02, 2012 Goldman, Sachs & Co. and affiliates Term loan facility	Nov. 02, 2012 Goldman, Sachs & Co. and affiliates ABL Facility	Nov. 02, 2012 KKR member	Nov. 02, 2012 KKR Term loan facility	Nov. 02, 2012 Buck Holdings, L.P. Credit Facilities
Related party transactions
Interest paid			$ 47.1	$ 46.4	$ 4.3	$ 1.2
Payments of financing costs							2.3			0.4	0.1		0.4
Incremental financing under the credit agreement for repurchase, redemption or acquisition of capital stock	250.0
Amendment fees		1.7												1.7
Interest rate swap payment								$ 2.5	$ 10.6
Number of members serving on the entity's board of directors												2