Commitments and contingencies (Detail) (USD $)	1 Months Ended	12 Months Ended
	Jan. 29, 1999	Jan. 30, 2015	Jan. 31, 2014 item	Feb. 01, 2013	Aug. 31, 2007
Commitments and contingencies
Number of store locations sold and leased back			233
Period for which asset was taken on lease under sale and leaseback transaction	23 years		15 years
Cash proceeds under sale and leaseback transaction			$ 281,600,000
Deferred gain under sale and leaseback transaction			67,200,000
Face value of promissory note purchased					34,300,000
Future minimum payments for operating leases
2015		793,274,000
2016		751,044,000
2017		703,892,000
2018		648,120,000
2019		584,508,000
Thereafter		3,145,663,000
Total minimum payments		6,626,501,000
Total minimum payments for capital leases		7,400,000
Present value of net minimum capital lease payments		5,900,000
Gross property and equipment recorded under capital lease		29,800,000	29,800,000
Accumulated depreciation on property and equipment recorded under capital lease		10,600,000	8,700,000
Operating lease rent expenses
Minimum rentals		776,103,000	674,849,000	599,138,000
Contingent rentals		9,099,000	12,058,000	15,150,000
Operating lease rent expenses		785,202,000	686,907,000	614,288,000
Amortization of leasehold interests		$ 5,800,000	$ 11,900,000	$ 16,900,000
Maximum
Commitments and contingencies
Typical period of primary lease term for operating lease, build-to-suit, maximum		15 years