Condensed consolidating financial information - Condensed consolidated statement of cash flows (Details) - USD ($) $ in Millions	6 Months Ended
	Aug. 04, 2018	Jul. 29, 2017
Cash flows from operating activities
Net cash provided by (used in) operating activities	$ 452.6	$ 409.8
Investing activities
Purchase of property, plant and equipment	(56.1)	(105.7)
Proceeds from sale of assets	5.5	0.0
Purchase of available-for-sale securities	(0.6)	(1.3)
Proceeds from available-for-sale securities	8.5	0.6
Net cash used in investing activities	(42.7)	(106.4)
Financing activities
Dividends paid on common shares	(40.6)	(39.0)
Dividends paid on redeemable convertible preferred shares	(15.6)	(19.1)
Intra-entity dividends paid	0.0
Repurchase of common shares	(485.0)	(460.0)
Proceeds from long-term debt		1,242.9
Proceeds from revolving credit facility	308.0	550.0
Repayments of revolving credit facility	(237.0)	(303.0)
Repayments of bank overdrafts	(8.1)	(3.1)
Other financing activities	(2.1)	(3.0)
Intra-entity activity, net	0.0	0.0
Net cash used in financing activities	(493.8)	(286.2)
Cash and cash equivalents at beginning of period	225.1	98.7
Decrease in cash and cash equivalents	(83.9)	17.2
Effect of exchange rate changes on cash and cash equivalents	(7.1)	3.2
Cash and cash equivalents at end of period	134.1	119.1
Consolidation, Eliminations
Cash flows from operating activities
Net cash provided by (used in) operating activities	(470.5)	(1,118.0)
Investing activities
Purchase of property, plant and equipment	0.0	0.0
Proceeds from sale of assets	0.0
Purchase of available-for-sale securities	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0
Net cash used in investing activities	0.0	0.0
Financing activities
Dividends paid on common shares	0.0	0.0
Dividends paid on redeemable convertible preferred shares	0.0	0.0
Intra-entity dividends paid	470.5
Repurchase of common shares	0.0
Proceeds from long-term debt		0.0
Proceeds from revolving credit facility	0.0	0.0
Repayments of revolving credit facility	0.0	0.0
Repayments of bank overdrafts	0.0
Other financing activities	0.0	0.0
Intra-entity activity, net	0.0	0.0
Net cash used in financing activities	470.5	1,118.0
Cash and cash equivalents at beginning of period	0.0	0.0
Decrease in cash and cash equivalents	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
Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	227.7	479.3
Investing activities
Purchase of property, plant and equipment	(55.1)	(105.6)
Proceeds from sale of assets	0.0
Purchase of available-for-sale securities	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0
Net cash used in investing activities	(55.1)	(105.6)
Financing activities
Dividends paid on common shares	0.0	0.0
Dividends paid on redeemable convertible preferred shares	0.0	0.0
Intra-entity dividends paid	0.0
Repurchase of common shares	0.0
Proceeds from long-term debt		0.0
Proceeds from revolving credit facility	308.0	550.0
Repayments of revolving credit facility	(237.0)	(303.0)
Repayments of bank overdrafts	(8.1)	(3.1)
Other financing activities	0.0	0.0
Intra-entity activity, net	(302.0)	208.1
Net cash used in financing activities	(252.5)	(357.0)
Cash and cash equivalents at beginning of period	150.5	70.3
Decrease in cash and cash equivalents	(79.9)	16.7
Effect of exchange rate changes on cash and cash equivalents	(6.0)	3.2
Cash and cash equivalents at end of period	64.6	90.2
Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	227.7	430.7
Investing activities
Purchase of property, plant and equipment	(1.0)	(0.1)
Proceeds from sale of assets	5.5
Purchase of available-for-sale securities	(0.6)	(1.3)
Proceeds from available-for-sale securities	8.5	0.6
Net cash used in investing activities	12.4	(0.8)
Financing activities
Dividends paid on common shares	0.0	0.0
Dividends paid on redeemable convertible preferred shares	0.0	0.0
Intra-entity dividends paid	(470.5)
Repurchase of common shares	0.0
Proceeds from long-term debt		1,242.9
Proceeds from revolving credit facility	0.0	0.0
Repayments of revolving credit facility	0.0	0.0
Repayments of bank overdrafts	0.0
Other financing activities	0.0	0.0
Intra-entity activity, net	227.2	(110.4)
Net cash used in financing activities	(243.3)	(428.4)
Cash and cash equivalents at beginning of period	72.8	26.6
Decrease in cash and cash equivalents	(3.2)	1.5
Effect of exchange rate changes on cash and cash equivalents	(1.1)
Cash and cash equivalents at end of period	68.5	28.1
Signet Jewelers Limited | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	467.5	617.7
Investing activities
Purchase of property, plant and equipment	0.0	0.0
Proceeds from sale of assets	0.0
Purchase of available-for-sale securities	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0
Net cash used in investing activities	0.0	0.0
Financing activities
Dividends paid on common shares	(40.6)	(39.0)
Dividends paid on redeemable convertible preferred shares	(15.6)	(19.1)
Intra-entity dividends paid	0.0
Repurchase of common shares	(485.0)
Proceeds from long-term debt		0.0
Proceeds from revolving credit facility	0.0	0.0
Repayments of revolving credit facility	0.0
Repayments of bank overdrafts	0.0
Other financing activities	(2.1)	(3.0)
Intra-entity activity, net	75.0	(97.6)
Net cash used in financing activities	(468.3)	(618.7)
Cash and cash equivalents at beginning of period	1.7	1.7
Decrease in cash and cash equivalents	(0.8)	(1.0)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Cash and cash equivalents at end of period	0.9	0.7
Signet UK Finance plc | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	0.2	0.1
Investing activities
Purchase of property, plant and equipment	0.0	0.0
Proceeds from sale of assets	0.0
Purchase of available-for-sale securities	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0
Net cash used in investing activities	0.0	0.0
Financing activities
Dividends paid on common shares	0.0	0.0
Dividends paid on redeemable convertible preferred shares	0.0	0.0
Intra-entity dividends paid	0.0
Repurchase of common shares	0.0
Proceeds from long-term debt		0.0
Proceeds from revolving credit facility	0.0	0.0
Repayments of revolving credit facility	0.0	0.0
Repayments of bank overdrafts	0.0	0.0
Other financing activities	0.0	0.0
Intra-entity activity, net	(0.2)	(0.1)
Net cash used in financing activities	(0.2)	(0.1)
Cash and cash equivalents at beginning of period	0.1	0.1
Decrease in cash and cash equivalents	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	0.1	0.1
Term Loan
Financing activities
Intra-entity dividends paid		0.0
Repurchase of common shares		(460.0)
Repayments of debt	(13.4)	(9.0)
Term Loan | Consolidation, Eliminations
Financing activities
Intra-entity dividends paid		1,118.0
Repurchase of common shares		0.0
Repayments of debt	0.0	0.0
Term Loan | Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Intra-entity dividends paid		(800.0)
Repurchase of common shares		0.0
Repayments of debt	(13.4)	(9.0)
Term Loan | Non-Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Intra-entity dividends paid		(318.0)
Repurchase of common shares		0.0
Repayments of debt	0.0
Term Loan | Signet Jewelers Limited | Reportable Legal Entities
Financing activities
Intra-entity dividends paid		0.0
Repurchase of common shares		(460.0)
Repayments of debt	0.0	0.0
Term Loan | Signet UK Finance plc | Reportable Legal Entities
Financing activities
Intra-entity dividends paid		0.0
Repurchase of common shares		0.0
Repayments of debt	0.0	0.0
Securitization facility
Financing activities
Repayments of debt	$ 0.0	(1,242.9)
Securitization facility | Consolidation, Eliminations
Financing activities
Repayments of debt		0.0
Securitization facility | Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Repayments of debt		0.0
Securitization facility | Non-Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Repayments of debt		(1,242.9)
Securitization facility | Signet Jewelers Limited | Reportable Legal Entities
Financing activities
Repayments of debt		0.0
Securitization facility | Signet UK Finance plc | Reportable Legal Entities
Financing activities
Repayments of debt		$ 0.0