Condensed consolidating financial information - Condensed consolidated balance sheet (Details) - USD ($) $ in Millions	Aug. 04, 2018	Feb. 03, 2018	Jul. 29, 2017	Jan. 28, 2017
Current assets:
Cash and cash equivalents	$ 134.1	$ 225.1	$ 119.1	$ 98.7
Accounts receivable, held for sale	4.6	0.0	1,055.6
Accounts receivable, net	6.5	692.5	664.5
Intra-entity receivables, net	0.0	0.0	0.0
Other receivables	83.4	87.2	91.2
Other current assets	155.9	158.2	128.5
Income taxes	119.2	2.6	1.8
Inventories	2,363.8	2,280.5	2,282.1
Total current assets	2,867.5	3,446.1	4,342.8
Non-current assets:
Property, plant and equipment, net	820.1	877.9	836.6
Goodwill	509.0	821.7	519.9	517.6
Intangible assets, net	341.3	481.5	413.9
Investment in subsidiaries	0.0		0.0
Intra-entity receivables, net	0.0		0.0
Other assets	169.6	171.2	165.1
Deferred tax assets	2.2	1.4	0.0
Retirement benefit asset	31.1	39.8	35.5
Total assets	4,740.8	5,839.6	6,313.8
Current liabilities:
Loans and overdrafts	111.4	44.0	939.4
Accounts payable	236.7	237.0	148.2
Intra-entity payables, net		0.0	0.0
Accrued expenses and other current liabilities	440.4	448.0	426.6
Deferred revenue	276.3	288.6	262.3
Income taxes	0.0	19.6	33.5
Total current liabilities	1,064.8	1,037.2	1,810.0
Non-current liabilities:
Long-term debt	671.1	688.2	705.3
Other liabilities	236.1	239.6	247.1
Deferred revenue	663.3	668.9	658.8
Deferred tax liabilities	91.0	92.3	103.3
Total liabilities	2,726.3	2,726.2	3,524.5
Shareholders’ equity:
Total shareholders’ equity	1,400.1	2,499.8	2,176.6
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	4,740.8	5,839.6	6,313.8
Consolidation, Eliminations
Current assets:
Cash and cash equivalents	0.0	0.0	0.0	0.0
Accounts receivable, held for sale	0.0		0.0
Accounts receivable, net	0.0	0.0	0.0
Intra-entity receivables, net	(181.4)	(169.8)	(278.6)
Other receivables	0.0	0.0	0.0
Other current assets	0.0	0.0	0.0
Income taxes	0.0	0.0	0.0
Inventories	0.0	0.0	0.0
Total current assets	(181.4)	(169.8)	(278.6)
Non-current assets:
Property, plant and equipment, net	0.0		0.0
Goodwill	0.0		0.0
Intangible assets, net	0.0	0.0	0.0
Investment in subsidiaries	(2,199.8)	(4,919.8)	(3,626.7)
Intra-entity receivables, net	(2,998.0)	(3,259.0)	(3,840.0)
Other assets	0.0		0.0
Deferred tax assets	0.0		0.0
Retirement benefit asset	0.0		0.0
Total assets	(5,379.2)	(8,348.6)	(7,745.3)
Current liabilities:
Loans and overdrafts	0.0	0.0	0.0
Accounts payable	0.0	0.0	0.0
Intra-entity payables, net	(181.4)	(169.8)	(278.6)
Accrued expenses and other current liabilities	0.0	0.0	0.0
Deferred revenue	0.0	0.0	0.0
Income taxes		0.0	0.0
Total current liabilities	(181.4)	(169.8)	(278.6)
Non-current liabilities:
Long-term debt			0.0
Intra-entity payables, net	(2,998.0)	(3,259.0)	(3,840.0)
Other liabilities			0.0
Deferred revenue			0.0
Deferred tax liabilities		0.0	0.0
Total liabilities	(3,179.4)	(3,428.8)	(4,118.6)
Shareholders’ equity:
Total shareholders’ equity	(2,199.8)	(4,919.8)	(3,626.7)
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	(5,379.2)	(8,348.6)	(7,745.3)
Guarantor Subsidiaries | Reportable Legal Entities
Current assets:
Cash and cash equivalents	64.6	150.5	90.2	70.3
Accounts receivable, held for sale	4.6		1,055.6
Accounts receivable, net	5.9	692.5	664.5
Intra-entity receivables, net	0.0	0.0	0.0
Other receivables	57.7	62.0	63.3
Other current assets	154.1	154.4	123.5
Income taxes	77.3	2.6	1.8
Inventories	2,298.6	2,201.3	2,214.7
Total current assets	2,662.8	3,263.3	4,213.6
Non-current assets:
Property, plant and equipment, net	812.8	870.1	832.6
Goodwill	206.3	516.4	516.3
Intangible assets, net	267.3	410.9	413.9
Investment in subsidiaries	335.9	1,163.6	532.8
Intra-entity receivables, net	0.0		0.0
Other assets	151.4	140.1	133.6
Deferred tax assets	2.1	1.3	0.0
Retirement benefit asset	31.1	39.8	35.5
Total assets	4,469.7	6,405.5	6,678.3
Current liabilities:
Loans and overdrafts	112.1	44.7	340.1
Accounts payable	206.6	202.2	142.7
Intra-entity payables, net	115.4	158.5	278.6
Accrued expenses and other current liabilities	394.2	397.5	375.9
Deferred revenue	263.9	276.2	262.3
Income taxes		36.7	30.1
Total current liabilities	1,092.2	1,115.8	1,429.7
Non-current liabilities:
Long-term debt	275.5	293.0	310.5
Intra-entity payables, net	2,998.0	3,259.0	3,840.0
Other liabilities	230.8	233.0	241.4
Deferred revenue	663.3	668.9	658.8
Deferred tax liabilities	74.6	76.7	103.3
Total liabilities	5,334.4	5,646.4	6,583.7
Shareholders’ equity:
Total shareholders’ equity	(864.7)	759.1	94.6
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	4,469.7	6,405.5	6,678.3
Non-Guarantor Subsidiaries | Reportable Legal Entities
Current assets:
Cash and cash equivalents	68.5	72.8	28.1	26.6
Accounts receivable, held for sale	0.0		0.0
Accounts receivable, net	0.6		0.0
Intra-entity receivables, net	178.3	166.9	162.4
Other receivables	25.7	25.2	27.9
Other current assets	1.8	3.8	5.0
Income taxes	41.9		0.0
Inventories	65.2	79.2	67.4
Total current assets	382.0	347.9	290.8
Non-current assets:
Property, plant and equipment, net	7.3	7.8	4.0
Goodwill	302.7	305.3	3.6
Intangible assets, net	74.0	70.6	0.0
Investment in subsidiaries	(243.3)	606.0	390.8
Intra-entity receivables, net	2,598.0	2,859.0	3,440.0
Other assets	18.2	31.1	31.5
Deferred tax assets	0.1	0.1	0.0
Retirement benefit asset	0.0		0.0
Total assets	3,139.0	4,227.8	4,160.7
Current liabilities:
Loans and overdrafts	0.0	0.0	600.0
Accounts payable	30.1	34.8	5.5
Intra-entity payables, net	0.0	0.0	0.0
Accrued expenses and other current liabilities	16.2	20.9	20.7
Deferred revenue	12.4	12.4	0.0
Income taxes		(16.9)	3.5
Total current liabilities	58.7	51.2	629.7
Non-current liabilities:
Long-term debt			0.0
Other liabilities	5.3	6.6	5.7
Deferred revenue			0.0
Deferred tax liabilities	16.4	15.6	0.0
Total liabilities	80.4	73.4	635.4
Shareholders’ equity:
Total shareholders’ equity	3,058.6	4,154.4	3,525.3
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	3,139.0	4,227.8	4,160.7
Signet Jewelers Limited | Reportable Legal Entities
Current assets:
Cash and cash equivalents	0.9	1.7	0.7	1.7
Accounts receivable, held for sale	0.0		0.0
Accounts receivable, net	0.0	0.0	0.0
Intra-entity receivables, net			113.1
Other receivables	0.0	0.0	0.0
Other current assets		0.0	0.0
Income taxes	0.0	0.0	0.0
Inventories	0.0	0.0	0.0
Total current assets	0.9	1.7	113.8
Non-current assets:
Property, plant and equipment, net	0.0		0.0
Goodwill	0.0		0.0
Intangible assets, net	0.0	0.0	0.0
Investment in subsidiaries	2,107.2	3,150.2	2,703.1
Intra-entity receivables, net	0.0		0.0
Other assets	0.0		0.0
Deferred tax assets	0.0		0.0
Retirement benefit asset	0.0		0.0
Total assets	2,108.1	3,151.9	2,816.9
Current liabilities:
Loans and overdrafts	0.0	0.0	0.0
Accounts payable	0.0	0.0	0.0
Intra-entity payables, net	66.0	11.3	0.0
Accrued expenses and other current liabilities	27.6	27.2	27.6
Deferred revenue	0.0	0.0	0.0
Income taxes		0.0	0.0
Total current liabilities	93.6	38.5	27.6
Non-current liabilities:
Long-term debt			0.0
Other liabilities			0.0
Deferred revenue			0.0
Deferred tax liabilities		0.0	0.0
Total liabilities	93.6	38.5	27.6
Shareholders’ equity:
Total shareholders’ equity	1,400.1	2,499.8	2,176.6
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	2,108.1	3,151.9	2,816.9
Signet UK Finance plc | Reportable Legal Entities
Current assets:
Cash and cash equivalents	0.1	0.1	0.1	$ 0.1
Accounts receivable, held for sale	0.0		0.0
Accounts receivable, net	0.0	0.0	0.0
Intra-entity receivables, net	3.1	2.9	3.1
Other receivables	0.0	0.0	0.0
Other current assets		0.0	0.0
Income taxes	0.0	0.0	0.0
Inventories	0.0	0.0	0.0
Total current assets	3.2	3.0	3.2
Non-current assets:
Property, plant and equipment, net	0.0	0.0	0.0
Goodwill	0.0	0.0	0.0
Intangible assets, net	0.0	0.0	0.0
Investment in subsidiaries	0.0	0.0	0.0
Intra-entity receivables, net	400.0	400.0	400.0
Other assets		0.0	0.0
Deferred tax assets	0.0	0.0	0.0
Retirement benefit asset	0.0	0.0	0.0
Total assets	403.2	403.0	403.2
Current liabilities:
Loans and overdrafts	(0.7)	(0.7)	(0.7)
Accounts payable	0.0	0.0	0.0
Intra-entity payables, net	0.0	0.0	0.0
Accrued expenses and other current liabilities	2.4	2.4	2.4
Deferred revenue	0.0	0.0	0.0
Income taxes		(0.2)	(0.1)
Total current liabilities	1.7	1.5	1.6
Non-current liabilities:
Long-term debt	395.6	395.2	394.8
Intra-entity payables, net		0.0	0.0
Other liabilities		0.0	0.0
Deferred revenue		0.0	0.0
Deferred tax liabilities		0.0	0.0
Total liabilities	397.3	396.7	396.4
Shareholders’ equity:
Total shareholders’ equity	5.9	6.3	6.8
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	403.2	403.0	403.2
Series A Redeemable Convertible Preferred Stock
Non-current liabilities:
Series A redeemable convertible preferred shares	614.4	613.6	612.7
Series A Redeemable Convertible Preferred Stock | Consolidation, Eliminations
Non-current liabilities:
Series A redeemable convertible preferred shares	0.0	0.0	0.0
Series A Redeemable Convertible Preferred Stock | Guarantor Subsidiaries | Reportable Legal Entities
Non-current liabilities:
Series A redeemable convertible preferred shares	0.0	0.0	0.0
Series A Redeemable Convertible Preferred Stock | Non-Guarantor Subsidiaries | Reportable Legal Entities
Non-current liabilities:
Series A redeemable convertible preferred shares	0.0	0.0	0.0
Series A Redeemable Convertible Preferred Stock | Signet Jewelers Limited | Reportable Legal Entities
Non-current liabilities:
Series A redeemable convertible preferred shares	614.4	613.6	612.7
Series A Redeemable Convertible Preferred Stock | Signet UK Finance plc | Reportable Legal Entities
Non-current liabilities:
Series A redeemable convertible preferred shares	$ 0.0	$ 0.0	$ 0.0