Condensed consolidating financial information - Condensed consolidated statement of cash flows (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 29, 2017	Apr. 30, 2016
Cash flows from operating activities
Net cash provided by (used in) operating activities	$ 56.8	$ 114.4
Investing activities
Purchase of property, plant and equipment	(56.2)	(39.3)
Investment in subsidiaries	0.0	0.0
Purchase of available-for-sale securities	(0.7)	(0.8)
Proceeds from available-for-sale securities	0.3	1.2
Net cash used in investing activities	(56.6)	(38.9)
Financing activities
Dividends paid on common shares	(17.8)	(17.5)
Dividends paid on redeemable convertible preferred shares	(11.3)	0.0
Intra-entity dividends paid	0.0	0.0
Proceeds from issuance of common shares	0.1	0.3
Excess tax benefit from exercise of share awards	0.0	1.3
Proceeds from long-term debt	666.5	696.5
Proceeds from revolving credit facility	128.0	99.0
Repayments of revolving credit facility	(121.0)	(55.0)
Repurchase of common shares	0.0	(125.0)
Net settlement of equity based awards	(1.1)	(4.6)
Capital lease payments	0.0	(0.1)
Proceeds from short-term borrowings	31.2	6.0
Intra-entity activity, net	0.0	0.0
Net cash provided by (used in) financing activities	3.6	(103.1)
Cash and cash equivalents at beginning of period	98.7	137.7
Decrease in cash and cash equivalents	3.8	(27.6)
Effect of exchange rate changes on cash and cash equivalents	(2.8)	2.9
Cash and cash equivalents at end of period	99.7	113.0
Consolidation, Eliminations
Cash flows from operating activities
Net cash provided by (used in) operating activities		(715.0)
Investing activities
Purchase of property, plant and equipment	0.0	0.0
Investment in subsidiaries		65.0
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	65.0
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	715.0
Proceeds from issuance of common shares	0.0	(65.0)
Excess tax benefit from exercise of share awards	0.0	0.0
Proceeds from long-term debt	0.0	0.0
Proceeds from revolving credit facility	0.0	0.0
Repayments of revolving credit facility	0.0	0.0
Repurchase of common shares	0.0	0.0
Net settlement of equity based awards	0.0	0.0
Capital lease payments	0.0	0.0
Proceeds from short-term borrowings	0.0
Intra-entity activity, net	0.0	0.0
Net cash provided by (used in) financing activities	0.0	650.0
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
Signet Jewelers Limited | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities		314.6
Investing activities
Purchase of property, plant and equipment	0.0	0.0
Investment in subsidiaries	0.0	(65.0)
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	(65.0)
Financing activities
Dividends paid on common shares	(17.8)	(17.5)
Dividends paid on redeemable convertible preferred shares	(11.3)
Intra-entity dividends paid	0.0	0.0
Proceeds from issuance of common shares	0.1	0.3
Excess tax benefit from exercise of share awards	0.0	0.0
Proceeds from long-term debt	0.0	0.0
Proceeds from revolving credit facility	0.0	0.0
Repayments of revolving credit facility	0.0
Repurchase of common shares		(125.0)
Net settlement of equity based awards	(1.1)	(4.6)
Capital lease payments	0.0	0.0
Proceeds from short-term borrowings	0.0
Intra-entity activity, net	29.4	(104.1)
Net cash provided by (used in) financing activities	(0.7)	(250.9)
Cash and cash equivalents at beginning of period	1.7	1.9
Decrease in cash and cash equivalents	(0.7)	(1.3)
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Cash and cash equivalents at end of period	1.0	0.6
Signet UK Finance plc | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	4.9	4.9
Investing activities
Purchase of property, plant and equipment	0.0	0.0
Investment in subsidiaries	0.0	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	0.0
Proceeds from issuance of common shares	0.0	0.0
Excess tax benefit from exercise of share awards	0.0	0.0
Proceeds from long-term debt	0.0	0.0
Proceeds from revolving credit facility	0.0	0.0
Repayments of revolving credit facility	0.0	0.0
Repurchase of common shares	0.0	0.0
Net settlement of equity based awards	0.0	0.0
Capital lease payments	0.0	0.0
Proceeds from short-term borrowings	0.0	0.0
Intra-entity activity, net	(4.9)	(4.9)
Net cash provided by (used in) financing activities	(4.9)	(4.9)
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
Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	(20.9)	240.5
Investing activities
Purchase of property, plant and equipment	(56.2)	(39.3)
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	(56.2)	(39.3)
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	(450.0)
Proceeds from issuance of common shares	0.0	65.0
Excess tax benefit from exercise of share awards	0.0	1.3
Proceeds from long-term debt	0.0	0.0
Proceeds from revolving credit facility	128.0	99.0
Repayments of revolving credit facility	(121.0)	(55.0)
Repurchase of common shares	0.0	0.0
Net settlement of equity based awards	0.0	0.0
Capital lease payments		0.1
Proceeds from short-term borrowings	31.2	6.0
Intra-entity activity, net	48.9	122.8
Net cash provided by (used in) financing activities	82.6	(218.5)
Cash and cash equivalents at beginning of period	70.3	102.0
Decrease in cash and cash equivalents	5.5	(17.3)
Effect of exchange rate changes on cash and cash equivalents	(2.9)	2.9
Cash and cash equivalents at end of period	72.9	87.6
Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	72.8	269.4
Investing activities
Purchase of available-for-sale securities	(0.7)	(0.8)
Proceeds from available-for-sale securities	0.3	1.2
Net cash used in investing activities	(0.4)	0.4
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	(265.0)
Proceeds from long-term debt	666.5	696.5
Proceeds from revolving credit facility	0.0	0.0
Repayments of revolving credit facility	0.0	0.0
Repurchase of common shares	0.0	0.0
Net settlement of equity based awards	0.0	0.0
Capital lease payments	0.0	0.0
Proceeds from short-term borrowings	0.0
Intra-entity activity, net	(73.4)	(13.8)
Net cash provided by (used in) financing activities	(73.4)	(278.8)
Cash and cash equivalents at beginning of period	26.6	33.7
Decrease in cash and cash equivalents	(1.0)	(9.0)
Effect of exchange rate changes on cash and cash equivalents	0.1
Cash and cash equivalents at end of period	25.7	24.7
Term Loan
Financing activities
Repayments of long-term debt	(4.5)	(7.5)
Term Loan | Consolidation, Eliminations
Financing activities
Repayments of long-term debt	0.0	0.0
Term Loan | Signet Jewelers Limited | Reportable Legal Entities
Financing activities
Repayments of long-term debt	0.0	0.0
Term Loan | Signet UK Finance plc | Reportable Legal Entities
Financing activities
Repayments of long-term debt	0.0	0.0
Term Loan | Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Repayments of long-term debt	(4.5)	(7.5)
Term Loan | Non-Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Repayments of long-term debt	0.0
Securitization facility
Financing activities
Repayments of long-term debt	(666.5)	(696.5)
Securitization facility | Consolidation, Eliminations
Financing activities
Repayments of long-term debt	0.0	0.0
Securitization facility | Signet Jewelers Limited | Reportable Legal Entities
Financing activities
Repayments of long-term debt	0.0	0.0
Securitization facility | Signet UK Finance plc | Reportable Legal Entities
Financing activities
Repayments of long-term debt	0.0	0.0
Securitization facility | Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Repayments of long-term debt	0.0	0.0
Securitization facility | Non-Guarantor Subsidiaries | Reportable Legal Entities
Financing activities
Repayments of long-term debt	$ (666.5)	$ (696.5)