Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Aug. 01, 2015		Aug. 02, 2014	Aug. 01, 2015		Aug. 02, 2014	Jan. 31, 2015
Segment Reporting Information [Line Items]
Sales		$ 1,410.6		$ 1,225.9	$ 2,941.2		$ 2,282.0
Operating income (loss)		100.8		83.5	277.0		234.2
Total assets		6,211.8		5,994.7	6,211.8		5,994.7	$ 6,327.6
Operating Segments
Segment Reporting Information [Line Items]
Sales		1,410.6		1,225.9	2,941.2		2,282.0
Operating income (loss)		100.8		83.5	277.0		234.2
Total assets		6,211.8		5,994.7	6,211.8		5,994.7	6,327.6
Sterling Jewelers | Operating Segments
Segment Reporting Information [Line Items]
Sales		858.5		810.4	1,802.7		1,713.9
Operating income (loss)		157.8		129.9	336.0		296.2
Total assets		3,607.9		3,296.4	3,607.9		3,296.4	3,647.3
Zale Jewelry | Operating Segments
Segment Reporting Information [Line Items]
Sales		336.4		215.0	709.3		215.0
Operating income (loss)		(2.0)	[1]	(8.0)	8.4	[1]	(8.0)
Total assets		1,831.9		1,881.6	1,831.9		1,881.6	1,903.6
Piercing Pagoda | Operating Segments
Segment Reporting Information [Line Items]
Sales		52.9		32.5	117.1		32.5
Operating income (loss)		(0.1)	[2]	(1.8)	5.0	[2]	(1.8)
Total assets		116.9		123.9	116.9		123.9	132.8
UK Jewelry | Operating Segments
Segment Reporting Information [Line Items]
Sales		159.1		162.9	305.6		314.6
Operating income (loss)		3.2		1.1	3.7		1.1
Total assets		432.2		475.4	432.2		475.4	413.5
Other | Operating Segments
Segment Reporting Information [Line Items]
Sales		3.7		5.1	6.5		6.0
Operating income (loss)	[3]	(58.1)		(37.7)	(76.1)		(53.3)
Total assets		$ 222.9		$ 217.4	$ 222.9		$ 217.4	$ 230.4

[1] Includes net operating loss of $4.4 million and $13.5 million related to the effects of purchase accounting associated with the acquisition of Zale Corporation for the 13 and 26 weeks ended August 1, 2015

[2] Includes net operating loss of $0.7 million and $3.0 million related to the effects of purchase accounting associated with the acquisition of Zale Corporation for the 13 weeks ended August 1, 2015 and $2.1 million for the 13 and 26 weeks ended August 2, 2014, respectively. See Note 3 for additional information.

[3] Includes $43.6 million and $50.0 million of transaction-related and integration expenses, including the impact of the appraisal rights legal settlement discussed in Note 19, for the 13 and 26 weeks ended August 1, 2015 and $30.8 million and $39.2 million of transaction-related and integration expenses for the 13 and 26 weeks ended August 2, 2014, respectively. Transaction costs include expenses associated with advisor fees for legal, tax, accounting and consulting services.