Basis of presentation and accounting policies - Impairment, Goodwill, Balance sheet detail (Detail) - USD ($)	12 Months Ended
	Jan. 29, 2016	Jan. 30, 2015	Jan. 31, 2014
Impairment of long-lived assets
Minimum period for which stores are open to be reviewed for impairment	3 years
Impairment charges included in SG&A expense	$ 5,900,000	$ 1,900,000	$ 500,000
Goodwill and other intangible assets
Impairment of intangible assets	0	0	$ 0
Accrued expenses and other liabilities
Compensation and benefits	111,191,000	78,645,000
Insurance	82,182,000	81,944,000
Taxes (other than taxes on income)	136,762,000	124,893,000
Other	136,987,000	128,278,000
Accrued expenses and other	467,122,000	413,760,000
Operating leases and related liabilities
Deferred rent liability	57,900,000	54,600,000
Contingent rent liability	4,000,000	4,800,000
Noncurrent Other liabilities
Insurance	137,798,000	140,916,000
Deferred rent	57,017,000	53,975,000
Deferred gain on sale leaseback	53,737,000	58,215,000
Other	26,731,000	32,203,000
Noncurrent other liabilities	$ 275,283,000	$ 285,309,000