Condensed consolidating financial information - Condensed Consolidated Income Statement (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 Income Statements, Captions [Line Items]
Sales	$ 2,154.7	$ 1,191.7	$ 1,420.1	$ 1,480.6	$ 2,293.1	$ 1,156.9	$ 1,399.6	$ 1,403.4	$ 6,247.1	$ 6,253.0	$ 6,408.4
Cost of sales									(4,024.1)	(4,063.0)	(4,047.6)
Gross margin	877.8	371.2	427.0	484.8	919.8	321.1	457.9	491.2	2,160.8	2,190.0	2,360.8
Selling, general and administrative expenses									(1,985.1)	(1,872.2)	(1,880.2)
Credit transaction, net									(167.4)	1.3	0.0
Restructuring charges									(63.7)	0.0	0.0
Goodwill and intangible impairments				(448.7)					(735.4)	0.0	0.0
Other operating income, net									26.2	260.8	282.6
Operating income (loss)									(764.6)	579.9	763.2
Intra-entity interest income (expense)									0.0	0.0
Interest expense, net									(39.7)	(52.7)	(49.4)
Other non-operating income									1.7	0.0	0.0
Income (loss) before income taxes									(802.6)	527.2	713.8
Income taxes									145.2	(7.9)	(170.6)
Equity in income of subsidiaries									0.0	0.0
Net income (loss)	$ (116.2)	$ (38.1)	$ (31.2)	$ (504.8)	$ 343.0	$ (12.1)	$ 85.2	$ 70.3	(657.4)	519.3	543.2
Dividends on redeemable convertible preferred shares									(32.9)	(32.9)	(11.9)
Net income (loss) attributable to common shareholders									(690.3)	486.4	531.3
Consolidation, Eliminations
Condensed Income Statements, Captions [Line Items]
Sales									0.0	0.0	0.0
Cost of sales									0.0	0.0	0.0
Gross margin									0.0	0.0	0.0
Selling, general and administrative expenses									0.0	0.0	0.0
Credit transaction, net									0.0	0.0
Restructuring charges									0.0
Goodwill and intangible impairments									0.0
Other operating income, net									0.0	0.0	0.0
Operating income (loss)									0.0	0.0	0.0
Intra-entity interest income (expense)									0.0	0.0	0.0
Interest expense, net									0.0	0.0	0.0
Other non-operating income									0.0
Income (loss) before income taxes									0.0	0.0	0.0
Income taxes									0.0	0.0	0.0
Equity in income of subsidiaries									2,465.2	(983.8)	(1,116.6)
Net income (loss)									2,465.2	(983.8)	(1,116.6)
Dividends on redeemable convertible preferred shares									0.0	0.0	0.0
Net income (loss) attributable to common shareholders									2,465.2	(983.8)	(1,116.6)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales									5,722.8	5,866.6	6,141.9
Cost of sales									(3,755.5)	(3,926.6)	(3,997.2)
Gross margin									1,910.8	1,940.0	2,144.7
Selling, general and administrative expenses									(1,833.4)	(1,738.2)	(1,775.1)
Credit transaction, net									(167.4)	1.3
Restructuring charges									(55.3)
Goodwill and intangible impairments									(470.4)
Other operating income, net									22.5	260.3	293.8
Operating income (loss)									(593.2)	463.4	663.4
Intra-entity interest income (expense)									(243.4)	(190.2)	(188.4)
Interest expense, net									(25.0)	(21.6)	(16.6)
Other non-operating income									1.7
Income (loss) before income taxes									(859.9)	251.6	458.4
Income taxes									133.0	(21.3)	(175.1)
Equity in income of subsidiaries									(1,043.1)	229.6	276.4
Net income (loss)									(1,770.0)	459.9	559.7
Dividends on redeemable convertible preferred shares									0.0	0.0	0.0
Net income (loss) attributable to common shareholders									(1,770.0)	459.9	559.7
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales									524.3	386.4	266.5
Cost of sales									(268.6)	(136.4)	(50.4)
Gross margin									250.0	250.0	216.1
Selling, general and administrative expenses									(150.7)	(132.1)	(103.8)
Credit transaction, net									0.0	0.0
Restructuring charges									(8.4)
Goodwill and intangible impairments									(265.0)
Other operating income, net									3.8	0.4	(11.2)
Operating income (loss)									(170.3)	118.3	101.1
Intra-entity interest income (expense)									229.1	171.4	169.6
Interest expense, net									0.2	(11.2)	(13.0)
Other non-operating income									0.0
Income (loss) before income taxes									59.0	278.5	257.7
Income taxes									13.0	13.2	4.3
Equity in income of subsidiaries									(770.4)	233.1	295.7
Net income (loss)									(698.4)	524.8	557.7
Dividends on redeemable convertible preferred shares									0.0	0.0	0.0
Net income (loss) attributable to common shareholders									(698.4)	524.8	557.7
Signet Jewelers Limited | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales									0.0	0.0	0.0
Cost of sales									0.0	0.0	0.0
Gross margin									0.0	0.0	0.0
Selling, general and administrative expenses									(1.0)	(1.9)	(1.3)
Credit transaction, net									0.0	0.0
Restructuring charges									0.0
Goodwill and intangible impairments									0.0
Other operating income, net									(0.1)	0.1	0.0
Operating income (loss)									(1.1)	(1.8)	(1.3)
Intra-entity interest income (expense)									(4.6)	0.0	0.0
Interest expense, net									0.0	0.0	0.0
Other non-operating income									0.0
Income (loss) before income taxes									(5.7)	(1.8)	(1.3)
Income taxes									0.0	0.0	0.0
Equity in income of subsidiaries									(651.7)	521.1	544.5
Net income (loss)									(657.4)	519.3	543.2
Net income (loss) attributable to common shareholders									(690.3)	486.4	531.3
Signet UK Finance plc | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales									0.0	0.0	0.0
Cost of sales									0.0	0.0	0.0
Gross margin									0.0	0.0	0.0
Selling, general and administrative expenses									0.0	0.0	0.0
Credit transaction, net									0.0	0.0
Restructuring charges									0.0
Goodwill and intangible impairments									0.0
Other operating income, net									0.0	0.0	0.0
Operating income (loss)									0.0	0.0	0.0
Intra-entity interest income (expense)									18.9	18.8	18.8
Interest expense, net									(14.9)	(19.9)	(19.8)
Other non-operating income									0.0
Income (loss) before income taxes									4.0	(1.1)	(1.0)
Income taxes									(0.8)	0.2	0.2
Equity in income of subsidiaries									0.0	0.0	0.0
Net income (loss)									3.2	(0.9)	(0.8)
Dividends on redeemable convertible preferred shares									0.0	0.0	0.0
Net income (loss) attributable to common shareholders									3.2	(0.9)	(0.8)
Restructuring
Condensed Income Statements, Captions [Line Items]
Cost of sales									(62.2)	$ 0.0	$ 0.0
Restructuring | Consolidation, Eliminations
Condensed Income Statements, Captions [Line Items]
Cost of sales									0.0
Restructuring | Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Cost of sales									(56.5)
Restructuring | Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Cost of sales									(5.7)
Restructuring | Signet Jewelers Limited | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Cost of sales									0.0
Restructuring | Signet UK Finance plc | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Cost of sales									$ 0.0