Revenue recognition - ESP Deferred Revenue Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	May 01, 2021	May 02, 2020
Change in Contract with Customer, Liability [Roll Forward]
ESP deferred revenue, beginning of period	$ 1,072.0
Plans sold	34.4	$ (5.0)
ESP deferred revenue, end of period	1,107.7	991.0
Extended Service Plan
Change in Contract with Customer, Liability [Roll Forward]
ESP deferred revenue, beginning of period	1,028.9	960.0
Plans sold	124.1	55.0
Revenue recognized	103.6	54.0
ESP deferred revenue, end of period	1,049.4	961.0
Extended Service Plan and Voucher Promotions
Change in Contract with Customer, Liability [Roll Forward]
Revenue recognized	$ 72.6	$ 44.5