Revenue recognition - ESP Deferred Revenue Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Feb. 01, 2020	Feb. 02, 2019
Change in Contract with Customer, Liability [Roll Forward]
ESP deferred revenue, beginning of period	$ 966.5
ESP deferred revenue, end of period	997.7	$ 966.5
Extended Service Plan
Change in Contract with Customer, Liability [Roll Forward]
ESP deferred revenue, beginning of period	927.6	916.1
Plans sold	405.1	395.0
Revenue recognized	(372.7)	(383.5)
ESP deferred revenue, end of period	960.0	$ 927.6
Extended Service Plan and Voucher Promotions
Change in Contract with Customer, Liability [Roll Forward]
Revenue recognized	$ (193.6)