Basis of presentation and accounting policies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Feb. 01, 2013 week item	Feb. 03, 2012 week	Jan. 28, 2011 week
Basis of presentation and accounting policies
Fiscal year, number of weeks	52	53	52
Business description
Number of stores through which entity sells general merchandise on a retail basis	10,506
Number of states which entity covers	40
Cash and cash equivalents
Maximum original maturity period at time of purchase of liquid investments classified as cash equivalents	3 months
Payments due from processors for electronic tender transactions classified as cash and cash equivalents	$ 45.2	$ 38.7
Minimum threshold of cash balances to be maintained as set by insurance regulators	20
Merchandise inventories
Excess of current cost over LIFO cost	101.9	100.5
LIFO provision	$ 1.4	$ 47.7	$ 5.3