Assets and liabilities measured at fair value (Details) - USD ($) $ in Thousands	Jul. 31, 2015	Jan. 30, 2015
Accrued expenses and other current liabilities
Liabilities:
Derivative financial instruments		$ 1,173
Reported amount | Current portion of long-term debt obligations
Liabilities:
Long-term obligations	$ 101,335
Reported amount | Long-term obligations
Liabilities:
Long-term obligations	2,761,794
Reported amount | Accrued expenses and other current liabilities
Liabilities:
Deferred compensation	5,663
Reported amount | Noncurrent Other liabilities
Liabilities:
Deferred compensation	18,820
Fair value measurements on recurring basis | Balance at the end of the period
Liabilities:
Long-term obligations	2,836,075
Deferred compensation	24,483
Fair value measurements on recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)
Liabilities:
Long-term obligations	1,775,824
Deferred compensation	24,483
Fair value measurements on recurring basis | Significant Other Observable Inputs (Level 2)
Liabilities:
Long-term obligations	$ 1,060,251