Deferred revenue - Deferred revenue rollforward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Nov. 01, 2014	Oct. 31, 2015	Nov. 01, 2014
Sterling Jewelers
Deferred Revenue Warranty [Roll Forward]
ESP deferred revenue, beginning of period	$ 691.4	$ 626.6	$ 668.9	$ 601.2
Plans sold	51.8	47.4	180.2	165.5
Revenue recognized	(58.5)	(47.7)	(164.4)	(140.4)
ESP deferred revenue, end of period	684.7	626.3	684.7	626.3
Zale
Deferred Revenue Arrangement [Line Items]
Product Warranty Accrual, Additions from Business Acquisition	0.0	0.0	0.0	93.3
Deferred Revenue Warranty [Roll Forward]
ESP deferred revenue, beginning of period	132.3	99.4	120.3	0.0
Plans sold	26.7	25.4	91.3	44.7
Revenue recognized	(26.4)	(20.1)	(79.0)	(33.3)
ESP deferred revenue, end of period	$ 132.6	$ 104.7	$ 132.6	$ 104.7