Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 29, 2016	Oct. 31, 2015	Oct. 29, 2016	Oct. 31, 2015	Jan. 30, 2016
Segment Reporting Information [Line Items]
Sales	$ 1,186.2	$ 1,216.4	$ 4,138.5	$ 4,157.6
Operating income (loss)	32.1	33.6	364.0	310.6
Total assets	6,487.5	6,325.9	6,487.5	6,325.9	$ 6,464.9
Sterling Jewelers
Segment Reporting Information [Line Items]
Sales	712.5	733.5	2,532.3	2,536.2
Operating income (loss)	78.6	77.2	417.8	413.2
Total assets	3,715.6	3,586.7	3,715.6	3,586.7	3,788.0
Zale Jewelry
Segment Reporting Information [Line Items]
Sales	282.4	281.9	994.8	991.2
Operating income (loss)	(19.3)	(18.3)	(0.5)	(9.9)
Total assets	2,061.7	1,977.6	2,061.7	1,977.6	1,955.1
Piercing Pagoda
Segment Reporting Information [Line Items]
Sales	53.4	48.0	179.4	165.1
Operating income (loss)	(5.4)	(6.0)	2.2	(1.0)
Total assets	136.1	135.4	136.1	135.4	141.8
UK Jewelry
Segment Reporting Information [Line Items]
Sales	130.3	149.4	419.5	455.0
Operating income (loss)	0.0	0.0	3.0	3.7
Total assets	407.1	470.5	407.1	470.5	427.8
Other
Segment Reporting Information [Line Items]
Sales	7.6	3.6	12.5	10.1
Operating income (loss)	(21.8)	(19.3)	(58.5)	(95.4)
Total assets	$ 167.0	$ 155.7	$ 167.0	$ 155.7	$ 152.2