Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Oct. 31, 2015		Nov. 01, 2014	Oct. 31, 2015		Nov. 01, 2014	Jan. 31, 2015
Segment Reporting Information [Line Items]
Sales		$ 1,216.4		$ 1,177.9	$ 4,157.6		$ 3,459.9
Operating income (loss)		33.6		10.7	310.6		244.9
Total assets		6,469.7		6,178.5	6,469.7		6,178.5	$ 6,327.6
Operating Segments
Segment Reporting Information [Line Items]
Sales		1,216.4		1,177.9	4,157.6		3,459.9
Operating income (loss)		33.6		10.7	310.6		244.9
Total assets		6,469.7		6,178.5	6,469.7		6,178.5	6,327.6
Sterling Jewelers | Operating Segments
Segment Reporting Information [Line Items]
Sales		733.5		692.8	2,536.2		2,406.7
Operating income (loss)		77.2		68.1	413.2		364.3
Total assets		3,756.6		3,477.2	3,756.6		3,477.2	3,647.3
Zale Jewelry | Operating Segments
Segment Reporting Information [Line Items]
Sales		281.9		289.1	991.2		504.1
Operating income (loss)		(18.3)	[1]	(26.7)	(9.9)	[1]	(34.7)
Total assets		1,941.6		1,942.6	1,941.6		1,942.6	1,903.6
Piercing Pagoda | Operating Segments
Segment Reporting Information [Line Items]
Sales		48.0		42.3	165.1		74.8
Operating income (loss)		(6.0)	[2]	(7.8)	(1.0)	[2]	(9.6)
Total assets		135.4		158.8	135.4		158.8	132.8
UK Jewelry | Operating Segments
Segment Reporting Information [Line Items]
Sales		149.4		151.0	455.0		465.6
Operating income (loss)		0.0		(2.7)	3.7		(1.6)
Total assets		470.5		484.5	470.5		484.5	413.5
Other | Operating Segments
Segment Reporting Information [Line Items]
Sales		3.6		2.7	10.1		8.7
Operating income (loss)	[3]	(19.3)		(20.2)	(95.4)		(73.5)
Total assets		$ 165.6		$ 115.4	$ 165.6		$ 115.4	$ 230.4

[1] Includes net operating loss of $3.6 million and $17.1 million related to the effects of purchase accounting associated with the acquisition of Zale Corporation for the 13 and 39 weeks ended October 31, 2015

[2] Includes net operating loss of $0.1 million and $3.1 million related to the effects of purchase accounting associated with the acquisition of Zale Corporation for the 13 and 39 weeks ended October 31, 2015 and $2.6 million and $4.7 million for the 13 and 39 weeks ended November 1, 2014, respectively. See Note 3 for additional information.

[3] Includes $9.8 million and $59.8 million of transaction-related and integration expenses, including the impact of the appraisal rights legal settlement discussed in Note 21, for the 13 and 39 weeks ended October 31, 2015 and $11.4 million and $50.6 million of transaction-related and integration expenses for the 13 and 39 weeks ended November 1, 2014, respectively. Transaction costs include expenses associated with advisor fees for legal, tax, accounting and consulting services