Leases - Lease assets and liabilities (Details) - USD ($) $ in Thousands	Jul. 31, 2019	Feb. 01, 2019
Assets and Liabilities, Lessee [Abstract]
Operating lease assets	$ 309,421	$ 341,200
Classification of operating lease assets	us-gaap:OperatingLeaseRightOfUseAsset
Total lease assets	$ 309,421
Current operating lease liabilities	$ 74,297
Classification current operating lease liabilities	us-gaap:OperatingLeaseLiabilityCurrent
Noncurrent operating liabilities	$ 272,632
Classification of noncurrent operating liabilities	us-gaap:OperatingLeaseLiabilityNoncurrent
Total lease liabilities	$ 346,929	$ 384,500