Assets and liabilities measured at fair value (Details) - USD ($) $ in Thousands	May 01, 2020	Jan. 31, 2020
Liabilities:
Current portion of long-term obligations	$ 580	$ 555
Long-term obligations	3,967,221	$ 2,911,438
Reported amount | Current portion of long-term debt obligations
Liabilities:
Current portion of long-term obligations	580
Reported amount | Long-term obligations
Liabilities:
Long-term obligations	3,967,221
Reported amount | Accrued expenses and other current liabilities
Liabilities:
Deferred compensation	2,466
Reported amount | Noncurrent Other liabilities
Liabilities:
Deferred compensation	25,955
Fair value measurements on recurring basis | Balance at the end of the period
Liabilities:
Long-term obligations	4,415,007
Deferred compensation	28,421
Fair value measurements on recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)
Liabilities:
Long-term obligations	4,410,667
Deferred compensation	28,421
Fair value measurements on recurring basis | Significant Other Observable Inputs (Level 2)
Liabilities:
Long-term obligations	$ 4,340