Condensed consolidating financial information - Condensed Consolidated Statement of Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Feb. 02, 2019	Nov. 03, 2018	Aug. 04, 2018	May 05, 2018	Feb. 03, 2018	Oct. 28, 2017	Jul. 29, 2017	Apr. 29, 2017	Feb. 02, 2019	Feb. 03, 2018	Jan. 28, 2017
Condensed Statement of Comprehensive Income [Line Items]
Net income		$ (116.2)	$ (38.1)	$ (31.2)	$ (504.8)	$ 343.0	$ (12.1)	$ 85.2	$ 70.3	$ (657.4)	$ 519.3	$ 543.2
Other comprehensive income (loss):
Foreign currency translation adjustments										(35.9)	50.9	(25.6)
Available-for-sale securities:
Unrealized gain (loss)	[1]									0.4	0.3	0.0
Impact from adoption of new accounting pronouncements	[2]									(0.8)
Cash flow hedges:
Unrealized gain (loss)										4.8	1.8	6.9
Reclassification adjustment for losses to net income										(1.5)	(3.5)	(0.6)
Pension plan:
Actuarial gain (loss)										(3.4)	0.0	(13.6)
Reclassification adjustment to net income for amortization of actuarial losses										0.7	2.2	1.2
Prior service costs										(6.5)	(0.5)	(0.4)
Reclassification adjustment to net income for amortization of net prior service credits										0.0	(1.1)	(1.5)
Net curtailment gain and settlement loss										0.0	(3.0)	0.0
Total other comprehensive (loss) income										(42.2)	47.1	(33.6)
Total comprehensive income										(699.6)	566.4	509.6
Consolidation, Eliminations
Condensed Statement of Comprehensive Income [Line Items]
Net income										2,465.2	(983.8)	(1,116.6)
Other comprehensive income (loss):
Foreign currency translation adjustments										35.9	(50.9)	25.6
Available-for-sale securities:
Unrealized gain (loss)										(0.4)	(0.3)
Impact from adoption of new accounting pronouncements										0.8
Cash flow hedges:
Unrealized gain (loss)										(4.8)	(1.8)	(6.9)
Reclassification adjustment for losses to net income										1.5	3.5	0.6
Pension plan:
Actuarial gain (loss)										3.4		13.6
Reclassification adjustment to net income for amortization of actuarial losses										(0.7)	(2.2)	(1.2)
Prior service costs										6.5	0.5	0.4
Reclassification adjustment to net income for amortization of net prior service credits											1.1	1.5
Net curtailment gain and settlement loss											3.0
Total other comprehensive (loss) income										42.2	(47.1)	33.6
Total comprehensive income										2,507.4	(1,030.9)	(1,083.0)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income										(1,770.0)	459.9	559.7
Other comprehensive income (loss):
Foreign currency translation adjustments										(35.4)	50.2	(31.2)
Available-for-sale securities:
Unrealized gain (loss)										0.0	0.0
Impact from adoption of new accounting pronouncements										0.0
Cash flow hedges:
Unrealized gain (loss)										4.8	1.8	6.9
Reclassification adjustment for losses to net income										(1.5)	(3.5)	(0.6)
Pension plan:
Actuarial gain (loss)										(3.4)		(13.6)
Reclassification adjustment to net income for amortization of actuarial losses										0.7	2.2	1.2
Prior service costs										(6.5)	(0.5)	(0.4)
Reclassification adjustment to net income for amortization of net prior service credits											(1.1)	(1.5)
Net curtailment gain and settlement loss											(3.0)
Total other comprehensive (loss) income										(41.3)	46.1	(39.2)
Total comprehensive income										(1,811.3)	506.0	520.5
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income										(698.4)	524.8	557.7
Other comprehensive income (loss):
Foreign currency translation adjustments										(0.5)	0.7	5.6
Available-for-sale securities:
Unrealized gain (loss)										0.4	0.3
Impact from adoption of new accounting pronouncements										(0.8)
Cash flow hedges:
Unrealized gain (loss)										0.0	0.0	0.0
Reclassification adjustment for losses to net income										0.0	0.0	0.0
Pension plan:
Actuarial gain (loss)										0.0		0.0
Reclassification adjustment to net income for amortization of actuarial losses										0.0	0.0	0.0
Prior service costs										0.0	0.0	0.0
Reclassification adjustment to net income for amortization of net prior service credits											0.0	0.0
Net curtailment gain and settlement loss											0.0
Total other comprehensive (loss) income										(0.9)	1.0	5.6
Total comprehensive income										(699.3)	525.8	563.3
Signet Jewelers Limited | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income										(657.4)	519.3	543.2
Other comprehensive income (loss):
Foreign currency translation adjustments										(35.9)	50.9	(25.6)
Available-for-sale securities:
Unrealized gain (loss)										0.4	0.3
Impact from adoption of new accounting pronouncements										(0.8)
Cash flow hedges:
Unrealized gain (loss)										4.8	1.8	6.9
Reclassification adjustment for losses to net income										(1.5)	(3.5)	(0.6)
Pension plan:
Actuarial gain (loss)										(3.4)		(13.6)
Reclassification adjustment to net income for amortization of actuarial losses										0.7	2.2	1.2
Prior service costs										(6.5)	(0.5)	(0.4)
Reclassification adjustment to net income for amortization of net prior service credits											(1.1)	(1.5)
Net curtailment gain and settlement loss											(3.0)
Total other comprehensive (loss) income										(42.2)	47.1	(33.6)
Total comprehensive income										(699.6)	566.4	509.6
Signet UK Finance plc | Reportable Legal Entities
Condensed Statement of Comprehensive Income [Line Items]
Net income										3.2	(0.9)	(0.8)
Other comprehensive income (loss):
Foreign currency translation adjustments										0.0	0.0	0.0
Available-for-sale securities:
Unrealized gain (loss)										0.0	0.0
Impact from adoption of new accounting pronouncements										0.0
Cash flow hedges:
Unrealized gain (loss)										0.0	0.0	0.0
Reclassification adjustment for losses to net income										0.0	0.0	0.0
Pension plan:
Actuarial gain (loss)										0.0		0.0
Reclassification adjustment to net income for amortization of actuarial losses										0.0	0.0	0.0
Prior service costs										0.0	0.0	0.0
Reclassification adjustment to net income for amortization of net prior service credits											0.0	0.0
Net curtailment gain and settlement loss											0.0
Total other comprehensive (loss) income										0.0	0.0	0.0
Total comprehensive income										$ 3.2	$ (0.9)	$ (0.8)

[1] During Fiscal 2019, amounts represent unrealized gains related to the Company’s available-for-sale debt securities. During Fiscal 2018, amounts represent unrealized gains related to the Company’s available-for-sale debt and equity securities.

[2] 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 2016-01.