Revenue recognition - Unamortized Deferred Selling Costs (Details) - USD ($) $ in Millions	Aug. 04, 2018	Feb. 03, 2018	Jul. 29, 2017
Revenue from Contract with Customer [Abstract]
Other current assets	$ 30.3	$ 30.9	$ 29.7
Other assets	88.4	89.5	87.2
Deferred ESP selling costs	$ 118.7	$ 120.4	$ 116.9

Amount of other miscellaneous assets expected to be realized or consumed after one year or normal operating cycle, if longer.

No definition available.

Name:	us-gaap_OtherAssetsMiscellaneousNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant