Condensed consolidating financial information - Condensed consolidated balance sheet (Details) - USD ($) $ in Millions	Oct. 28, 2017	Jan. 28, 2017	Oct. 29, 2016	Jan. 30, 2016
Current assets:
Cash and cash equivalents	$ 113.4	$ 98.7	$ 82.7	$ 137.7
Accounts receivable, net	640.1	1,858.0	1,581.1
Intra-entity receivables, net	0.0	0.0	0.0
Other receivables	80.3	95.9	74.2
Other current assets	145.0	136.3	146.8
Income taxes	17.3	4.4	20.8
Inventories	2,466.1	2,449.3	2,649.4
Total current assets	3,462.2	4,642.6	4,555.0
Non-current assets:
Property, plant and equipment, net	855.1	822.9	791.1
Goodwill	867.1	517.6	517.0	515.5
Intangible assets, net	410.4	417.0	419.8
Investment in subsidiaries	0.0		0.0
Intra-entity receivables, net	0.0		0.0
Other assets	169.1	165.1	157.5
Deferred tax assets	1.3	0.7	0.0
Retirement benefit asset	35.5	31.9	47.1
Total assets	5,800.7	6,597.8	6,487.5
Current liabilities:
Loans and overdrafts	291.8	91.1	288.8
Accounts payable	324.9	255.7	382.2
Intra-entity payables, net		0.0	0.0
Accrued expenses and other current liabilities	430.5	478.2	402.9
Deferred revenue	270.3	276.9	256.7
Income taxes	0.0	101.8	4.4
Total current liabilities	1,317.5	1,203.7	1,335.0
Non-current liabilities:
Long-term debt	696.8	1,317.9	1,324.2
Other liabilities	244.4	213.7	219.9
Deferred revenue	646.1	659.0	632.1
Deferred tax liabilities	143.8	101.4	133.4
Total liabilities	3,048.6	3,495.7	3,644.6
Shareholders’ equity:
Total shareholders’ equity	2,139.0	2,490.2	2,231.2
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	5,800.7	6,597.8	6,487.5
Consolidation, Eliminations
Current assets:
Cash and cash equivalents	0.0	0.0	0.0	0.0
Accounts receivable, net	0.0	0.0	0.0
Intra-entity receivables, net	(355.3)	(157.8)	(329.3)
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	(355.3)	(157.8)	(329.3)
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	(3,874.4)	(4,430.1)	(3,873.6)
Intra-entity receivables, net	(3,235.0)	(4,050.0)	(4,055.0)
Other assets	0.0		0.0
Deferred tax assets	0.0		0.0
Retirement benefit asset	0.0		0.0
Total assets	(7,464.7)	(8,637.9)	(8,257.9)
Current liabilities:
Loans and overdrafts	0.0	0.0	0.0
Accounts payable	0.0	0.0	0.0
Intra-entity payables, net	(355.3)	(157.8)	(329.3)
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	0.0
Total current liabilities	(355.3)	(157.8)	(329.3)
Non-current liabilities:
Long-term debt			0.0
Intra-entity payables, net	(3,235.0)	(4,050.0)	(4,055.0)
Other liabilities			0.0
Deferred revenue			0.0
Deferred tax liabilities		0.0	0.0
Total liabilities	(3,590.3)	(4,207.8)	(4,384.3)
Shareholders’ equity:
Total shareholders’ equity	(3,874.4)	(4,430.1)	(3,873.6)
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	(7,464.7)	(8,637.9)	(8,257.9)
Guarantor Subsidiaries | Reportable Legal Entities
Current assets:
Cash and cash equivalents	59.1	70.3	55.7	102.0
Accounts receivable, net	638.7	1,858.0	1,581.1
Intra-entity receivables, net	0.0	145.1	0.0
Other receivables	55.6	71.1	52.0
Other current assets	140.0	131.4	140.3
Income taxes	17.3	4.4	35.6
Inventories	2,392.6	2,371.8	2,578.3
Total current assets	3,303.3	4,652.1	4,443.0
Non-current assets:
Property, plant and equipment, net	847.5	818.5	786.4
Goodwill	515.0	514.0	513.4
Intangible assets, net	410.4	417.0	419.8
Investment in subsidiaries	834.5	721.6	586.7
Intra-entity receivables, net	0.0		0.0
Other assets	136.9	134.8	126.2
Deferred tax assets	1.2	0.6	0.0
Retirement benefit asset	35.5	31.9	47.1
Total assets	6,084.3	7,290.5	6,922.6
Current liabilities:
Loans and overdrafts	292.5	91.8	289.5
Accounts payable	291.0	248.2	376.4
Intra-entity payables, net	355.3		329.3
Accrued expenses and other current liabilities	372.1	429.2	360.1
Deferred revenue	259.6	275.5	256.7
Income taxes	(24.3)	115.5	3.9
Total current liabilities	1,546.2	1,160.2	1,615.9
Non-current liabilities:
Long-term debt	301.8	323.6	330.1
Intra-entity payables, net	3,235.0	4,050.0	4,055.0
Other liabilities	238.8	208.7	213.7
Deferred revenue	646.1	659.0	632.1
Deferred tax liabilities	143.6	101.4	133.5
Total liabilities	6,111.5	6,502.9	6,980.3
Shareholders’ equity:
Total shareholders’ equity	(27.2)	787.6	(57.7)
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	6,084.3	7,290.5	6,922.6
Non-Guarantor Subsidiaries | Reportable Legal Entities
Current assets:
Cash and cash equivalents	53.8	26.6	26.7	33.7
Accounts receivable, net	1.4		0.0
Intra-entity receivables, net	262.1		278.9
Other receivables	24.7	24.8	22.2
Other current assets	5.0	4.9	6.5
Income taxes	0.0		(14.9)
Inventories	73.5	77.5	71.1
Total current assets	420.5	133.8	390.5
Non-current assets:
Property, plant and equipment, net	7.6	4.4	4.7
Goodwill	352.1	3.6	3.6
Intangible assets, net	0.0	0.0	0.0
Investment in subsidiaries	346.2	590.9	474.4
Intra-entity receivables, net	2,835.0	3,647.1	3,647.4
Other assets	32.2	30.3	31.3
Deferred tax assets	0.1	0.1	0.0
Retirement benefit asset	0.0		0.0
Total assets	3,993.7	4,410.2	4,551.9
Current liabilities:
Loans and overdrafts	0.0	0.0	0.0
Accounts payable	33.9	7.5	5.8
Intra-entity payables, net	0.0	157.8	0.0
Accrued expenses and other current liabilities	23.7	16.6	15.5
Deferred revenue	10.7	1.4	0.0
Income taxes	24.5	(13.5)	0.5
Total current liabilities	92.8	169.8	21.8
Non-current liabilities:
Long-term debt		600.0	600.0
Other liabilities	5.6	5.0	6.2
Deferred revenue			0.0
Deferred tax liabilities	0.2	0.0	(0.1)
Total liabilities	98.6	774.8	627.9
Shareholders’ equity:
Total shareholders’ equity	3,895.1	3,635.4	3,924.0
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	3,993.7	4,410.2	4,551.9
Signet Jewelers Limited | Reportable Legal Entities
Current assets:
Cash and cash equivalents	0.4	1.7	0.2	1.9
Accounts receivable, net	0.0	0.0	0.0
Intra-entity receivables, net	85.6	12.7	50.4
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	86.0	14.4	50.6
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	2,693.7	3,117.6	2,812.5
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	2,779.7	3,132.0	2,863.1
Current liabilities:
Loans and overdrafts	0.0	0.0	0.0
Accounts payable	0.0	0.0	0.0
Intra-entity payables, net	0.0	0.0	0.0
Accrued expenses and other current liabilities	27.6	29.9	20.2
Deferred revenue	0.0	0.0	0.0
Income taxes	0.0	0.0	0.0
Total current liabilities	27.6	29.9	20.2
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	27.6	29.9	20.2
Shareholders’ equity:
Total shareholders’ equity	2,139.0	2,490.2	2,231.2
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	2,779.7	3,132.0	2,863.1
Signet UK Finance plc | Reportable Legal Entities
Current assets:
Cash and cash equivalents	0.1	0.1	0.1	$ 0.1
Accounts receivable, net	0.0	0.0	0.0
Intra-entity receivables, net	7.6	0.0	0.0
Other receivables	0.0	0.0	0.0
Other current assets		0.0	0.0
Income taxes	0.0	0.0	0.1
Inventories	0.0	0.0	0.0
Total current assets	7.7	0.1	0.2
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	402.9	407.6
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	407.7	403.0	407.8
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	7.1	2.5	7.1
Deferred revenue	0.0	0.0	0.0
Income taxes	(0.2)	(0.2)	0.0
Total current liabilities	6.2	1.6	6.4
Non-current liabilities:
Long-term debt	395.0	394.3	394.1
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	401.2	395.9	400.5
Shareholders’ equity:
Total shareholders’ equity	6.5	7.1	7.3
Total liabilities, redeemable convertible preferred shares and shareholders’ equity	407.7	403.0	407.8
Series A Redeemable Convertible Preferred Stock
Non-current liabilities:
Series A redeemable convertible preferred shares	613.1	611.9	611.7
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	613.1	611.9	611.7
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