Revenue recognition - ESP Deferred Revenue Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 30, 2021	Feb. 01, 2020
Change in Contract with Customer, Liability [Roll Forward]
ESP deferred revenue, beginning of period	$ 997.7
ESP deferred revenue, end of period	1,072.0	$ 997.7
Extended Service Plan
Change in Contract with Customer, Liability [Roll Forward]
ESP deferred revenue, beginning of period	960.0	927.6
Plans sold	337.4	405.1
Revenue recognized	(268.5)	(372.7)
ESP deferred revenue, end of period	1,028.9	960.0
Extended Service Plan and Voucher Promotions
Change in Contract with Customer, Liability [Roll Forward]
Revenue recognized	$ (163.5)	$ (193.6)