Organization and summary of significant accoutning policies - Narrative (Details) $ in Millions		3 Months Ended						12 Months Ended
	Oct. 05, 2016 USD ($) shares	Feb. 03, 2018	Oct. 28, 2017	Jul. 29, 2017	Apr. 29, 2017	Jan. 28, 2017	Jan. 30, 2016	Feb. 03, 2018 USD ($) Segment	Jan. 28, 2017 USD ($)	Jan. 30, 2016 USD ($)
Organization and critical accounting policies [Abstract]
Number of reportable segments | Segment								5
Percent of annual sales		40.00%	20.00%	20.00%	20.00%
Advertising and promotional costs [Abstract]
Advertising expense								$ 360.5	$ 380.6	$ 384.2
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%
Minimum
Organization and critical accounting policies [Abstract]
Operating income expected in fourth quarter								45.00%
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]
Operating income expected in fourth quarter								55.00%
Property, Plant and Equipment [Abstract]
Period over which amortization is charged for capitalized payroll for internal use computer projects								5 years
Sterling Jewelers | Minimum
Organization and critical accounting policies [Abstract]
Operating income expected in fourth quarter								40.00%
Sterling Jewelers | Maximum
Organization and critical accounting policies [Abstract]
Operating income expected in fourth quarter								45.00%
Theft Protection | Zale
Revenue Recognition [Abstract]
Product warranty								2 years
Lifetime Warranty | Sterling Jewelers
Revenue Recognition [Abstract]
Deferred revenue recognition period of extended service plan sales						2 years		17 years
Revenue recognized percentage In relation to costs expected to be incurred within first two years						57.00%	57.00%	57.00%	42.00%	42.00%
Lifetime Warranty | Zale
Revenue Recognition [Abstract]
Revenue recognized percentage In relation to costs expected to be incurred within first two years								69.00%	69.00%	69.00%
Product warranty								10 years
Watch Warranty | Zale
Revenue Recognition [Abstract]
Product warranty								2 years
Breakage Warranty | Zale
Revenue Recognition [Abstract]
Product warranty								1 year
Jewelry Replacement Plan | Sterling Jewelers
Revenue Recognition [Abstract]
Deferred revenue recognition period of extended service plan sales								3 years
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Abstract]
Redeemable convertible preferred stock, shares issued | shares	625,000
Preferred stock, purchase price	$ 625.0