Organization and summary of significant accoutning policies - Narrative (Details)	3 Months Ended		12 Months Ended
	Feb. 02, 2019 USD ($)	May 05, 2018 USD ($)	Feb. 02, 2019 USD ($) Segment	Feb. 03, 2018 USD ($)	Jan. 28, 2017 USD ($)
Organization and critical accounting policies [Abstract]
Number of reportable segments | Segment			3
Revenue Recognition [Abstract]
Sales returns reserve	$ 16,800,000		$ 16,800,000	$ 13,500,000
Percentage of revenue recognized within the first two years	55.00%		55.00%	58.00%
Advertising and promotional costs [Abstract]
Advertising expense			$ 387,800,000	$ 360,500,000	$ 380,600,000
In-house customer finance programs [Abstract]
Interest-free financing period			1 year
Accrued interest suspension period			90 days
Accounts Receivable [Abstract]
Loss allowance, maturity period			90 days
Percentage allowance on losses			100.00%
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, impairment loss		$ 286,700,000	$ (521,200,000)	$ 0
Minimum
Organization and critical accounting policies [Abstract]
Percent of annual sales	35.00%
Property, Plant and Equipment [Abstract]
Period over which amortization is charged for capitalized payroll for internal use computer projects			3 years
Maximum
Organization and critical accounting policies [Abstract]
Percent of annual sales	40.00%
Property, Plant and Equipment [Abstract]
Period over which amortization is charged for capitalized payroll for internal use computer projects			5 years
Sterling Jewelers
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, impairment loss		521,200,000
Impairment of intangible assets (excluding goodwill)		$ 214,200,000
Lifetime Warranty | Sterling Jewelers
Revenue Recognition [Abstract]
Deferred revenue recognition period			17 years