Condensed consolidating financial information - Condensed consolidated income statement (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 29, 2016	Oct. 31, 2015	Oct. 29, 2016	Oct. 31, 2015
Condensed Income Statements, Captions [Line Items]
Sales	$ 1,186.2	$ 1,216.4	$ 4,138.5	$ 4,157.6
Cost of sales	(836.2)	(848.7)	(2,723.2)	(2,733.2)
Gross margin	350.0	367.7	1,415.3	1,424.4
Selling, general and administrative expenses	(386.5)	(395.0)	(1,264.9)	(1,301.0)
Other operating income, net	68.6	60.9	213.6	187.2
Operating income	32.1	33.6	364.0	310.6
Intra-entity interest income (expense)	0.0	0.0	0.0	0.0
Interest expense, net	(12.7)	(11.7)	(36.4)	(33.8)
Income before income taxes	19.4	21.9	327.6	276.8
Income taxes	(2.4)	(6.9)	(81.9)	(80.8)
Equity in income of subsidiaries	0.0	0.0	0.0	0.0
Net income	17.0	15.0	245.7	196.0
Dividends on redeemable convertible preferred shares	(2.2)	0.0	(2.2)	0.0
Net income attributable to common shareholders	14.8	15.0	243.5	196.0
Consolidation, Eliminations
Condensed Income Statements, Captions [Line Items]
Sales	0.0	0.0	0.0	0.0
Cost of sales	0.0	0.0	0.0	0.0
Gross margin	0.0	0.0	0.0	0.0
Selling, general and administrative expenses	0.0	0.0	0.0	0.0
Other operating income, net	0.0	0.0	0.0	0.0
Operating income	0.0	0.0	0.0	0.0
Intra-entity interest income (expense)	0.0	0.0	0.0	0.0
Interest expense, net	0.0	0.0	0.0	0.0
Income before income taxes	0.0	0.0	0.0	0.0
Income taxes	0.0	0.0	0.0	0.0
Equity in income of subsidiaries	58.2	27.3	(388.5)	(359.8)
Net income	58.2	27.3	(388.5)	(359.8)
Dividends on redeemable convertible preferred shares	0.0		0.0
Net income attributable to common shareholders	58.2	27.3	(388.5)	(359.8)
Signet Jewelers Limited | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales	0.0	0.0	0.0	0.0
Cost of sales	0.0	0.0	0.0	0.0
Gross margin	0.0	0.0	0.0	0.0
Selling, general and administrative expenses	(0.3)	(0.4)	(0.9)	(1.6)
Other operating income, net	0.0	0.0	0.0	0.0
Operating income	(0.3)	(0.4)	(0.9)	(1.6)
Intra-entity interest income (expense)	0.0	0.0	0.0	0.0
Interest expense, net	0.0	0.0	0.0	0.0
Income before income taxes	(0.3)	(0.4)	(0.9)	(1.6)
Income taxes	0.0	0.0	0.0	0.0
Equity in income of subsidiaries	17.3	15.4	246.6	197.6
Net income	17.0	15.0	245.7	196.0
Net income attributable to common shareholders	14.8	15.0	243.5	196.0
Signet UK Finance plc | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales	0.0	0.0	0.0	0.0
Cost of sales	0.0	0.0	0.0	0.0
Gross margin	0.0	0.0	0.0	0.0
Selling, general and administrative expenses	0.0	0.0	0.0	0.0
Other operating income, net	0.0	0.0	0.0	0.0
Operating income	0.0	0.0	0.0	0.0
Intra-entity interest income (expense)	4.7	4.7	14.1	14.1
Interest expense, net	(5.0)	(5.2)	(14.8)	(15.0)
Income before income taxes	(0.3)	(0.5)	(0.7)	(0.9)
Income taxes	0.0	0.1	0.1	0.2
Equity in income of subsidiaries	0.0	0.0	0.0	0.0
Net income	(0.3)	(0.4)	(0.6)	(0.7)
Dividends on redeemable convertible preferred shares	0.0		0.0
Net income attributable to common shareholders	(0.3)	(0.4)	(0.6)	(0.7)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales	1,121.8	1,197.4	3,955.0	4,099.7
Cost of sales	(821.7)	(844.4)	(2,688.0)	(2,719.6)
Gross margin	300.1	353.0	1,267.0	1,380.1
Selling, general and administrative expenses	(362.0)	(387.1)	(1,190.9)	(1,276.2)
Other operating income, net	75.6	61.8	227.6	186.0
Operating income	13.7	27.7	303.7	289.9
Intra-entity interest income (expense)	(47.8)	(46.7)	(142.2)	(139.8)
Interest expense, net	(4.5)	(3.8)	(12.1)	(10.7)
Income before income taxes	(38.6)	(22.8)	149.4	139.4
Income taxes	15.1	9.3	(61.5)	(65.4)
Equity in income of subsidiaries	(51.9)	(30.8)	48.8	69.9
Net income	(75.4)	(44.3)	136.7	143.9
Dividends on redeemable convertible preferred shares	0.0		0.0
Net income attributable to common shareholders	(75.4)	(44.3)	136.7	143.9
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales	64.4	19.0	183.5	57.9
Cost of sales	(14.5)	(4.3)	(35.2)	(13.6)
Gross margin	49.9	14.7	148.3	44.3
Selling, general and administrative expenses	(24.2)	(7.5)	(73.1)	(23.2)
Other operating income, net	(7.0)	(0.9)	(14.0)	1.2
Operating income	18.7	6.3	61.2	22.3
Intra-entity interest income (expense)	43.1	42.0	128.1	125.7
Interest expense, net	(3.2)	(2.7)	(9.5)	(8.1)
Income before income taxes	58.6	45.6	179.8	139.9
Income taxes	(17.5)	(16.3)	(20.5)	(15.6)
Equity in income of subsidiaries	(23.6)	(11.9)	93.1	92.3
Net income	17.5	17.4	252.4	216.6
Dividends on redeemable convertible preferred shares	0.0		0.0
Net income attributable to common shareholders	$ 17.5	$ 17.4	$ 252.4	$ 216.6