Revenue recognition - Narrative (Details) - USD ($) $ in Millions		12 Months Ended
		Jan. 30, 2021	Feb. 01, 2020	Feb. 02, 2019	Feb. 03, 2018
Disaggregation of Revenue [Line Items]
Capitalized contract cost reclassified		$ (111.3)	$ (103.6)
Shareholders' equity reclassification, adoption of ASU 2014-09		1,190.3	1,222.6	$ 1,201.6	$ 2,499.8
Cumulative Effect, Period of Adoption, Adjustment
Disaggregation of Revenue [Line Items]
Revenue recognized				111.2
Capitalized contract cost reclassified					16.5
Shareholders' equity reclassification, adoption of ASU 2014-09	[1]				$ (16.5)
Extended Service Plans and Lifetime Warranty Agreements
Disaggregation of Revenue [Line Items]
Capitalized contract cost, amortization		$ 26.3	$ 29.5	$ 52.4
North America | Extended Service Plans and Lifetime Warranty Agreements
Disaggregation of Revenue [Line Items]
Revenue, performance obligation, description of timing		17 years
North America | Jewelry Replacement Plan
Disaggregation of Revenue [Line Items]
Revenue, performance obligation, description of timing		three years

[1] Reflects reclassifications to retained earnings related to 1) unrealized gains related to the Company’s equity security investments as of February 3, 2018 from AOCI associated with the adoption of ASU 2016-01 and 2) deferred costs associated with the sale of extended service plans due to the adoption of ASU 2014-09.