Condensed consolidating financial information - Condensed consolidated statement of comprehensive income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 29, 2016	Oct. 31, 2015	Oct. 29, 2016	Oct. 31, 2015
Condensed Statement of Comprehensive Income [Line Items]
Net income	$ 17.0	$ 15.0	$ 245.7	$ 196.0
Other comprehensive income (loss):
Foreign currency translation adjustments	(28.9)	(4.2)	(38.0)	(1.4)
Available-for-sale securities:
Unrealized loss	(0.2)	(0.1)	0.2	(0.4)
Cash flow hedges:
Unrealized (loss) gain	1.9	1.1	8.2	(10.3)
Reclassification adjustment for losses to net income	(0.1)	0.9	1.6	2.2
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss	0.4	0.7	1.0	2.1
Reclassification adjustment to net income for amortization of prior service (credits) costs	(0.4)	(0.5)	(1.2)	(1.4)
Total other comprehensive (loss) income	(27.3)	(2.1)	(28.2)	(9.2)
Total comprehensive income (loss)	(10.3)	12.9	217.5	186.8
Consolidation, Eliminations
Condensed Statement of Comprehensive Income [Line Items]
Net income	58.2	27.3	(388.5)	(359.8)
Other comprehensive income (loss):
Foreign currency translation adjustments	28.9	4.2	38.0	1.4
Available-for-sale securities:
Unrealized loss	0.2	0.1	(0.2)	0.4
Cash flow hedges:
Unrealized (loss) gain	(1.9)	(1.1)	(8.2)	10.3
Reclassification adjustment for losses to net income	0.1	(0.9)	(1.6)	(2.2)
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss	(0.4)	(0.7)	(1.0)	(2.1)
Reclassification adjustment to net income for amortization of prior service (credits) costs	0.4	0.5	1.2	1.4
Total other comprehensive (loss) income	27.3	2.1	28.2	9.2
Total comprehensive income (loss)	85.5	29.4	(360.3)	(350.6)
Signet Jewelers Limited | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income	17.0	15.0	245.7	196.0
Other comprehensive income (loss):
Foreign currency translation adjustments	(28.9)	(4.2)	(38.0)	(1.4)
Available-for-sale securities:
Unrealized loss	(0.2)	(0.1)	0.2	(0.4)
Cash flow hedges:
Unrealized (loss) gain	1.9	1.1	8.2	(10.3)
Reclassification adjustment for losses to net income	(0.1)	0.9	1.6	2.2
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss	0.4	0.7	1.0	2.1
Reclassification adjustment to net income for amortization of prior service (credits) costs	(0.4)	(0.5)	(1.2)	(1.4)
Total other comprehensive (loss) income	(27.3)	(2.1)	(28.2)	(9.2)
Total comprehensive income (loss)	(10.3)	12.9	217.5	186.8
Signet UK Finance plc | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income	(0.3)	(0.4)	(0.6)	(0.7)
Other comprehensive income (loss):
Foreign currency translation adjustments	0.0	0.0	0.0	0.0
Available-for-sale securities:
Unrealized loss	0.0	0.0	0.0	0.0
Cash flow hedges:
Unrealized (loss) gain	0.0	0.0	0.0	0.0
Reclassification adjustment for losses to net income	0.0	0.0	0.0	0.0
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss	0.0	0.0	0.0	0.0
Reclassification adjustment to net income for amortization of prior service (credits) costs	0.0	0.0	0.0	0.0
Total other comprehensive (loss) income	0.0	0.0	0.0	0.0
Total comprehensive income (loss)	(0.3)	(0.4)	(0.6)	(0.7)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income	(75.4)	(44.3)	136.7	143.9
Other comprehensive income (loss):
Foreign currency translation adjustments	(32.5)	(6.4)	(45.2)	(0.4)
Available-for-sale securities:
Unrealized loss	0.0	0.0	0.0	0.0
Cash flow hedges:
Unrealized (loss) gain	1.9	1.1	8.2	(10.3)
Reclassification adjustment for losses to net income	(0.1)	0.9	1.6	2.2
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss	0.4	0.7	1.0	2.1
Reclassification adjustment to net income for amortization of prior service (credits) costs	(0.4)	(0.5)	(1.2)	(1.4)
Total other comprehensive (loss) income	(30.7)	(4.2)	(35.6)	(7.8)
Total comprehensive income (loss)	(106.1)	(48.5)	101.1	136.1
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income	17.5	17.4	252.4	216.6
Other comprehensive income (loss):
Foreign currency translation adjustments	3.6	2.2	7.2	(1.0)
Available-for-sale securities:
Unrealized loss	(0.2)	(0.1)	0.2	(0.4)
Cash flow hedges:
Unrealized (loss) gain	0.0	0.0	0.0	0.0
Reclassification adjustment for losses to net income	0.0	0.0	0.0	0.0
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss	0.0	0.0	0.0	0.0
Reclassification adjustment to net income for amortization of prior service (credits) costs	0.0	0.0	0.0	0.0
Total other comprehensive (loss) income	3.4	2.1	7.4	(1.4)
Total comprehensive income (loss)	$ 20.9	$ 19.5	$ 259.8	$ 215.2