Condensed consolidating financial information - Condensed Consolidated Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Feb. 02, 2019	Feb. 03, 2018	Jan. 28, 2017
Cash flows from operating activities:
Net cash provided by (used in) operating activities	$ 697.7	$ 1,940.5	$ 678.3
Investing activities
Purchase of property, plant and equipment	(133.5)	(237.4)	(278.0)
Proceeds from sale of assets	5.5	0.0	0.0
Investment in subsidiaries	0.0	0.0	0.0
Purchase of available-for-sale securities	(0.6)	(2.4)	(10.4)
Proceeds from available-for-sale securities	9.6	2.2	10.0
Acquisition of R2Net Inc., net of cash acquired		(331.8)
Net cash used in investing activities	(119.0)	(569.4)	(278.4)
Financing activities
Dividends paid on common shares	(79.0)	(76.5)	(75.6)
Dividends paid on redeemable convertible preferred shares	(31.2)	(34.7)	0.0
Intra-entity dividends paid	0.0	0.0	0.0
Repurchase of common shares	(485.0)	(460.0)	(1,000.0)
Proceeds from issuance of common shares	0.0	0.3	2.1
Net settlement of equity based awards		(2.9)	(4.9)
Proceeds from issuance of redeemable convertible preferred shares, net of issuance costs	0.0	0.0	611.3
Excess tax benefit from exercise of share awards			2.4
Proceeds from revolving credit facility	787.0	814.0	1,270.0
Repayments of revolving credit facility	(787.0)	(870.0)	(1,214.0)
Payment of debt issuance costs		(1.4)	(2.7)
Principal payments under capital lease obligations			(0.2)
Proceeds from (repayment of) short-term borrowings	25.9	(0.1)	(10.2)
Other financing activities	(2.1)	(4.0)	(3.3)
Intra-entity activity, net	0.0	0.0	0.0
Net cash used in financing activities	(602.7)	(1,253.6)	(438.2)
Cash and cash equivalents at beginning of period	225.1	98.7	137.7
Increase (decrease) in cash and cash equivalents	(24.0)	117.5	(38.3)
Effect of exchange rate changes on cash and cash equivalents	(5.7)	8.9	(0.7)
Cash and cash equivalents at end of period	195.4	225.1	98.7
Consolidation, Eliminations
Cash flows from operating activities:
Net cash provided by (used in) operating activities	(660.8)	(1,269.9)	(1,630.1)
Investing activities
Purchase of property, plant and equipment	0.0	0.0	0.0
Proceeds from sale of assets	0.0
Investment in subsidiaries	80.0	244.9	610.0
Purchase of available-for-sale securities	0.0	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0	0.0
Acquisition of R2Net Inc., net of cash acquired		0.0
Net cash used in investing activities	80.0	244.9	610.0
Financing activities
Dividends paid on common shares	0.0	0.0	0.0
Dividends paid on redeemable convertible preferred shares	0.0	0.0
Intra-entity dividends paid	660.8	1,269.9	1,630.1
Repurchase of common shares	0.0	0.0	0.0
Proceeds from issuance of common shares	(80.0)	(244.9)	(610.0)
Net settlement of equity based awards		0.0	0.0
Proceeds from issuance of redeemable convertible preferred shares, net of issuance costs			0.0
Excess tax benefit from exercise of share awards			0.0
Proceeds from revolving credit facility	0.0	0.0	0.0
Repayments of revolving credit facility	0.0	0.0	0.0
Payment of debt issuance costs		0.0	0.0
Principal payments under capital lease obligations			0.0
Proceeds from (repayment of) short-term borrowings	0.0	0.0	0.0
Other financing activities	0.0
Intra-entity activity, net	0.0		0.0
Net cash used in financing activities	580.8	1,025.0	1,020.1
Cash and cash equivalents at beginning of period	0.0	0.0	0.0
Increase (decrease) in cash and cash equivalents	0.0	0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0		0.0
Cash and cash equivalents at end of period	0.0	0.0	0.0
Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used in) operating activities	363.8	1,856.7	724.8
Investing activities
Purchase of property, plant and equipment	(128.9)	(236.3)	(277.9)
Proceeds from sale of assets	0.0
Investment in subsidiaries		(25.0)
Purchase of available-for-sale securities	0.0	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0	0.0
Acquisition of R2Net Inc., net of cash acquired		(331.8)
Net cash used in investing activities	(128.9)	(593.1)	(277.9)
Financing activities
Dividends paid on common shares	0.0	0.0	0.0
Dividends paid on redeemable convertible preferred shares	0.0	0.0
Intra-entity dividends paid		(800.0)	(730.0)
Repurchase of common shares	0.0	0.0	0.0
Proceeds from issuance of common shares	80.0	219.9	610.0
Net settlement of equity based awards		0.0	0.0
Proceeds from issuance of redeemable convertible preferred shares, net of issuance costs			0.0
Excess tax benefit from exercise of share awards			2.4
Proceeds from revolving credit facility	787.0	814.0	1,270.0
Repayments of revolving credit facility	(787.0)	(870.0)	(1,214.0)
Payment of debt issuance costs		(1.4)	(2.1)
Principal payments under capital lease obligations			(0.2)
Proceeds from (repayment of) short-term borrowings	25.9	(0.1)	(10.2)
Other financing activities	0.0
Intra-entity activity, net	(307.9)	(532.2)	(386.6)
Net cash used in financing activities	(233.3)	(1,192.1)	(477.1)
Cash and cash equivalents at beginning of period	150.5	70.3	102.0
Increase (decrease) in cash and cash equivalents	1.6	71.5	(30.2)
Effect of exchange rate changes on cash and cash equivalents	(5.4)	8.7	(1.5)
Cash and cash equivalents at end of period	146.7	150.5	70.3
Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used in) operating activities	336.6	586.0	525.6
Investing activities
Purchase of property, plant and equipment	(4.6)	(1.1)	(0.1)
Proceeds from sale of assets	5.5
Purchase of available-for-sale securities	(0.6)	(2.4)	(10.4)
Proceeds from available-for-sale securities	9.6	2.2	10.0
Acquisition of R2Net Inc., net of cash acquired		0.0
Net cash used in investing activities	9.9	(1.3)	(0.5)
Financing activities
Dividends paid on common shares	0.0	0.0	0.0
Dividends paid on redeemable convertible preferred shares	0.0	0.0
Intra-entity dividends paid	(660.8)	(469.9)	(900.1)
Repurchase of common shares	0.0	0.0	0.0
Proceeds from issuance of common shares		25.0	0.0
Net settlement of equity based awards		0.0	0.0
Excess tax benefit from exercise of share awards			0.0
Proceeds from revolving credit facility	0.0	0.0	0.0
Repayments of revolving credit facility	0.0	0.0	0.0
Payment of debt issuance costs		0.0	(0.6)
Principal payments under capital lease obligations			0.0
Proceeds from (repayment of) short-term borrowings	0.0	0.0	0.0
Other financing activities	0.0
Intra-entity activity, net	290.2	506.2	367.7
Net cash used in financing activities	(370.6)	(538.7)	(533.0)
Cash and cash equivalents at beginning of period	72.8	26.6	33.7
Increase (decrease) in cash and cash equivalents	(24.1)	46.0	(7.9)
Effect of exchange rate changes on cash and cash equivalents	(0.3)	0.2	0.8
Cash and cash equivalents at end of period	48.4	72.8	26.6
Signet Jewelers Limited | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used in) operating activities	653.1	767.8	1,057.9
Investing activities
Purchase of property, plant and equipment	0.0	0.0	0.0
Proceeds from sale of assets	0.0
Investment in subsidiaries	(80.0)	(219.9)	(610.0)
Purchase of available-for-sale securities	0.0	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0	0.0
Acquisition of R2Net Inc., net of cash acquired		0.0
Net cash used in investing activities	(80.0)	(219.9)	(610.0)
Financing activities
Dividends paid on common shares	(79.0)	(76.5)	(75.6)
Dividends paid on redeemable convertible preferred shares	(31.2)	(34.7)
Intra-entity dividends paid	0.0	0.0	0.0
Repurchase of common shares	(485.0)	(460.0)	(1,000.0)
Proceeds from issuance of common shares		0.3	2.1
Net settlement of equity based awards		(2.9)	(4.9)
Proceeds from issuance of redeemable convertible preferred shares, net of issuance costs			611.3
Excess tax benefit from exercise of share awards			0.0
Proceeds from revolving credit facility	0.0	0.0	0.0
Repayments of revolving credit facility	0.0	0.0	0.0
Payment of debt issuance costs		0.0	0.0
Principal payments under capital lease obligations			0.0
Proceeds from (repayment of) short-term borrowings	0.0	0.0	0.0
Other financing activities	(2.1)
Intra-entity activity, net	22.7	25.9	19.0
Net cash used in financing activities	(574.6)	(547.9)	(448.1)
Cash and cash equivalents at beginning of period	1.7	1.7	1.9
Increase (decrease) in cash and cash equivalents	(1.5)		(0.2)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents at end of period	0.2	1.7	1.7
Signet UK Finance plc | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used in) operating activities	5.0	(0.1)	0.1
Investing activities
Purchase of property, plant and equipment	0.0	0.0	0.0
Proceeds from sale of assets	0.0
Investment in subsidiaries	0.0	0.0	0.0
Purchase of available-for-sale securities	0.0	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0	0.0
Acquisition of R2Net Inc., net of cash acquired		0.0
Net cash used in investing activities	0.0	0.0	0.0
Financing activities
Dividends paid on common shares	0.0	0.0	0.0
Dividends paid on redeemable convertible preferred shares	0.0	0.0
Intra-entity dividends paid	0.0	0.0	0.0
Repurchase of common shares	0.0	0.0	0.0
Proceeds from issuance of common shares		0.0	0.0
Net settlement of equity based awards		0.0	0.0
Proceeds from issuance of redeemable convertible preferred shares, net of issuance costs			0.0
Excess tax benefit from exercise of share awards			0.0
Proceeds from revolving credit facility	0.0	0.0	0.0
Repayments of revolving credit facility	0.0	0.0	0.0
Payment of debt issuance costs		0.0	0.0
Principal payments under capital lease obligations			0.0
Proceeds from (repayment of) short-term borrowings	0.0	0.0	0.0
Other financing activities	0.0
Intra-entity activity, net	(5.0)	0.1	(0.1)
Net cash used in financing activities	(5.0)	0.1	(0.1)
Cash and cash equivalents at beginning of period	0.1	0.1	0.1
Increase (decrease) in cash and cash equivalents		0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents at end of period	0.1	0.1	0.1
Term Loan
Financing activities
Proceeds from debt	0.0	350.0	0.0
Repayments of term loan	(31.3)	(372.3)	(16.4)
Term Loan | Consolidation, Eliminations
Financing activities
Proceeds from debt		0.0
Repayments of term loan	0.0	0.0	0.0
Term Loan | Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Proceeds from debt		350.0
Repayments of term loan	(31.3)	(372.3)	(16.4)
Term Loan | Non-Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Proceeds from debt		0.0
Repayments of term loan	0.0	0.0	0.0
Term Loan | Signet Jewelers Limited | Reportable Legal Entities
Financing activities
Proceeds from debt		0.0
Repayments of term loan	0.0	0.0	0.0
Term Loan | Signet UK Finance plc | Reportable Legal Entities
Financing activities
Proceeds from debt		0.0
Repayments of term loan	0.0	0.0	0.0
Securitization facility
Financing activities
Proceeds from debt	0.0	1,745.9	2,404.1
Repayments of term loan	$ 0.0	(2,345.9)	(2,404.1)
Securitization facility | Consolidation, Eliminations
Financing activities
Proceeds from debt		0.0	0.0
Repayments of term loan		0.0	0.0
Securitization facility | Non-Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Proceeds from debt		1,745.9	2,404.1
Repayments of term loan		(2,345.9)	(2,404.1)
Securitization facility | Signet Jewelers Limited | Reportable Legal Entities
Financing activities
Proceeds from debt		0.0	0.0
Repayments of term loan		0.0	0.0
Securitization facility | Signet UK Finance plc | Reportable Legal Entities
Financing activities
Proceeds from debt		0.0	0.0
Repayments of term loan		$ 0.0	$ 0.0