Condensed consolidating financial information - Condensed consolidated statement of comprehensive income (loss) (Details) - USD ($) $ in Millions		3 Months Ended
		May 04, 2019	May 05, 2018
Condensed Statement of Comprehensive Income [Line Items]
Net income		$ (10.0)	$ (496.6)
Other comprehensive income (loss):
Foreign currency translation adjustments		(2.0)	(21.7)
Available-for-sale securities:
Unrealized loss		0.3	(0.2)
Impact from adoption of new accounting pronouncements	[1]	0.0	(0.8)
Cash flow hedges:
Unrealized gain (loss)		(3.2)
Reclassification adjustment for gains to net income		(0.4)
Unrealized gain (loss)			1.5
Reclassification adjustment for gains to net income			(0.3)
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss		0.2	0.3
Reclassification adjustment to net income for amortization of prior service credits		0.0	(0.1)
Total other comprehensive income (loss)		(5.1)	(21.3)
Total comprehensive income (loss)		(15.1)	(517.9)
Consolidation, Eliminations
Condensed Statement of Comprehensive Income [Line Items]
Net income		154.4	1,628.7
Other comprehensive income (loss):
Foreign currency translation adjustments		2.0	21.7
Available-for-sale securities:
Unrealized loss		(0.3)	0.2
Impact from adoption of new accounting pronouncements			0.8
Cash flow hedges:
Unrealized gain (loss)		3.2
Reclassification adjustment for gains to net income		0.4
Unrealized gain (loss)			(1.5)
Reclassification adjustment for gains to net income			0.3
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss		(0.2)	(0.3)
Reclassification adjustment to net income for amortization of prior service credits			0.1
Total other comprehensive income (loss)		5.1	21.3
Total comprehensive income (loss)		159.5	1,650.0
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income		(148.7)	(1,132.8)
Other comprehensive income (loss):
Foreign currency translation adjustments		(2.0)	(21.5)
Available-for-sale securities:
Unrealized loss		0.0	0.0
Impact from adoption of new accounting pronouncements			0.0
Cash flow hedges:
Unrealized gain (loss)		(3.2)
Reclassification adjustment for gains to net income		(0.4)
Unrealized gain (loss)			1.5
Reclassification adjustment for gains to net income			(0.3)
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss		0.2	0.3
Reclassification adjustment to net income for amortization of prior service credits			(0.1)
Total other comprehensive income (loss)		(5.4)	(20.1)
Total comprehensive income (loss)		(154.1)	(1,152.9)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income		(5.5)	(495.7)
Other comprehensive income (loss):
Foreign currency translation adjustments			(0.2)
Available-for-sale securities:
Unrealized loss		0.3	(0.2)
Impact from adoption of new accounting pronouncements			(0.8)
Cash flow hedges:
Unrealized gain (loss)		0.0
Reclassification adjustment for gains to net income		0.0
Unrealized gain (loss)			0.0
Reclassification adjustment for gains to net income			0.0
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss		0.0	0.0
Reclassification adjustment to net income for amortization of prior service credits			0.0
Total other comprehensive income (loss)		0.3	(1.2)
Total comprehensive income (loss)		(5.2)	(496.9)
Signet Jewelers Limited | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income		(10.0)	(496.6)
Other comprehensive income (loss):
Foreign currency translation adjustments		(2.0)	(21.7)
Available-for-sale securities:
Unrealized loss		0.3	(0.2)
Impact from adoption of new accounting pronouncements			(0.8)
Cash flow hedges:
Unrealized gain (loss)		(3.2)
Reclassification adjustment for gains to net income		(0.4)
Unrealized gain (loss)			1.5
Reclassification adjustment for gains to net income			(0.3)
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss		0.2	0.3
Reclassification adjustment to net income for amortization of prior service credits			(0.1)
Total other comprehensive income (loss)		(5.1)	(21.3)
Total comprehensive income (loss)		(15.1)	(517.9)
Signet UK Finance plc | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income		(0.2)	(0.2)
Other comprehensive income (loss):
Foreign currency translation adjustments		0.0	0.0
Available-for-sale securities:
Unrealized loss		0.0	0.0
Impact from adoption of new accounting pronouncements			0.0
Cash flow hedges:
Unrealized gain (loss)		0.0
Reclassification adjustment for gains to net income		0.0
Unrealized gain (loss)			0.0
Reclassification adjustment for gains to net income			0.0
Pension plan:
Reclassification adjustment to net income for amortization of actuarial loss		0.0	0.0
Reclassification adjustment to net income for amortization of prior service credits			0.0
Total other comprehensive income (loss)		0.0	0.0
Total comprehensive income (loss)		$ (0.2)	$ (0.2)

[1] Adjustment reflects the reclassification of unrealized gains related to the Company’s available-for-sale equity securities as of February 3, 2018 from AOCI into retained earnings associated with the adoption of ASU 2016-1.