Basis of presentation and accounting policies (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 30, 2015 USD ($)	Oct. 31, 2014 USD ($)	Oct. 30, 2015 USD ($)	Oct. 31, 2014 USD ($)	Jan. 29, 2016 period	Jan. 30, 2015 USD ($) period
Fiscal year, number of weeks | period					52	52
Merchandise inventories
LIFO provision (benefit)	$ (1,700)	$ 2,200	$ (2,300)	$ 3,100
Debt issue costs
Deferred Finance Costs, Noncurrent, Net	19,151		19,151			$ 15,462
Adjustment for accounting standards update
Debt issue costs
Deferred Finance Costs, Noncurrent, Net	$ 19,200		$ 19,200			$ 15,500