Condensed consolidating financial information - Condensed consolidated statement of cash flows (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Nov. 01, 2014	Oct. 31, 2015	Nov. 01, 2014
Cash flows from operating activities
Net cash provided by (used in) operating activities	$ (121.9)	$ (208.1)	$ 88.7	$ (24.2)
Investing activities
Purchase of property, plant and equipment	(71.9)	(75.1)	(170.8)	(165.1)
Investment in subsidiaries	0.0		0.0	0.0
Purchase of available-for-sale securities	(1.9)	(3.0)	(3.8)	(4.2)
Proceeds from available-for-sale securities	0.0	1.5	3.6	2.5
Acquisition of Zale Corporation, net of cash acquired	0.0	0.0	0.0	(1,429.2)
Net cash used in investing activities	(73.8)	(76.6)	(171.0)	(1,596.0)
Financing activities
Dividends paid	(17.5)	(14.4)	(49.6)	(40.8)
Intra-entity dividends paid	0.0	0.0	0.0	0.0
Proceeds from issuance of common shares	3.1	2.2	3.3	4.2
Excess tax benefit from exercise of share awards	0.0	0.0	5.1	7.7
Proceeds from long-term debt	542.6	493.4	1,738.9	2,222.4
Repayments of long-term debt	(550.1)	(498.4)	(1,756.4)	(829.0)
Repayments of Lines of Credit	(30.0)	0.0	(30.0)	0.0
Payment of debt issuance costs	0.0	(2.1)	0.0	(20.5)
Proceeds from Lines of Credit	177.0	145.0	177.0	145.0
Payments for Repurchase of Common Stock	30.0	7.4	111.9	29.8
Payments Related to Tax Withholding for Share-based Compensation	0.0	3.0	8.3	18.1
Repayments of Long-term Capital Lease Obligations	(0.2)	(0.3)	(0.8)	(0.5)
Proceeds from (Repayments of) Short-term Debt	18.5	43.0	(1.5)	20.8
Intra-entity activity, net	0.0	0.0	0.0	0.0
Net cash used in financing activities	113.4	158.0	(34.2)	1,461.4
Cash and cash equivalents at beginning of period	159.8	215.0	193.6	247.6
Decrease in cash and cash equivalents	(82.3)	(126.7)	(116.5)	(158.8)
Effect of exchange rate changes on cash and cash equivalents	(0.3)	(0.7)	0.1	(1.2)
Cash and cash equivalents at end of period	77.2	87.6	77.2	87.6
Consolidation, Eliminations
Cash flows from operating activities
Net cash provided by (used in) operating activities	(100.0)	(100.0)	(100.0)	(150.0)
Investing activities
Purchase of property, plant and equipment	0.0	0.0	0.0	0.0
Investment in subsidiaries		1.4		8.8
Purchase of available-for-sale securities	0.0	0.0	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0	0.0	0.0
Acquisition of Zale Corporation, net of cash acquired		0.0	0.0	0.0
Net cash used in investing activities	0.0	1.4	0.0	8.8
Financing activities
Dividends paid	0.0	0.0	0.0	0.0
Intra-entity dividends paid	(100.0)	100.0	(100.0)	950.0
Proceeds from issuance of common shares		(1.4)	0.0	(808.8)
Excess tax benefit from exercise of share awards	0.0	0.0	0.0	0.0
Proceeds from long-term debt	0.0	0.0	0.0	0.0
Repayments of long-term debt	0.0	0.0	0.0	0.0
Repayments of Lines of Credit	0.0	0.0	0.0	0.0
Payment of debt issuance costs	0.0	0.0	0.0	0.0
Proceeds from Lines of Credit	0.0	0.0	0.0	0.0
Payments for Repurchase of Common Stock	0.0	0.0	0.0	0.0
Payments Related to Tax Withholding for Share-based Compensation	0.0	0.0	0.0	0.0
Repayments of Long-term Capital Lease Obligations	0.0	0.0	0.0	0.0
Proceeds from (Repayments of) Short-term Debt	0.0	0.0	0.0	0.0
Intra-entity activity, net	0.0	0.0	0.0
Net cash used in financing activities	100.0	98.6	100.0	141.2
Cash and cash equivalents at beginning of period	0.0	0.0	0.0	0.0
Decrease in cash and cash equivalents	0.0	0.0	0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0	0.0
Cash and cash equivalents at end of period	0.0	0.0	0.0	0.0
Signet Jewelers Limited | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	99.3	99.3	98.4	148.4
Investing activities
Purchase of property, plant and equipment	0.0	0.0	0.0	0.0
Investment in subsidiaries	0.0	0.0	0.0	0.0
Purchase of available-for-sale securities	0.0	0.0	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0	0.0	0.0
Acquisition of Zale Corporation, net of cash acquired		0.0	0.0	0.0
Net cash used in investing activities	0.0	0.0	0.0	0.0
Financing activities
Dividends paid	(17.5)	(14.4)	(49.6)	(40.8)
Intra-entity dividends paid	0.0	0.0	0.0	0.0
Proceeds from issuance of common shares	3.1	2.2	3.3	4.2
Excess tax benefit from exercise of share awards	0.0	0.0	0.0	0.0
Proceeds from long-term debt	0.0	0.0	0.0	0.0
Repayments of long-term debt	0.0	0.0	0.0	0.0
Repayments of Lines of Credit	0.0	0.0	0.0	0.0
Payment of debt issuance costs	0.0	0.0	0.0	0.0
Proceeds from Lines of Credit	0.0	0.0	0.0	0.0
Payments for Repurchase of Common Stock	30.0	7.4	111.9	29.8
Payments Related to Tax Withholding for Share-based Compensation		3.0	8.3	18.1
Repayments of Long-term Capital Lease Obligations	0.0	0.0	0.0	0.0
Proceeds from (Repayments of) Short-term Debt	0.0	0.0	0.0	0.0
Intra-entity activity, net	(52.0)	(75.2)	69.1	(62.4)
Net cash used in financing activities	(96.4)	(97.8)	(97.4)	(146.9)
Cash and cash equivalents at beginning of period	0.2	1.4	2.1	1.4
Decrease in cash and cash equivalents	2.9	1.5	1.0	1.5
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0	0.0
Cash and cash equivalents at end of period	3.1	2.9	3.1	2.9
Signet UK Finance plc | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	4.4	4.5	4.6	8.3
Investing activities
Purchase of property, plant and equipment	0.0	0.0	0.0	0.0
Investment in subsidiaries	0.0	0.0	0.0	0.0
Purchase of available-for-sale securities	0.0	0.0	0.0	0.0
Proceeds from available-for-sale securities	0.0	0.0	0.0	0.0
Acquisition of Zale Corporation, net of cash acquired		0.0	0.0	0.0
Net cash used in investing activities	0.0	0.0	0.0	0.0
Financing activities
Dividends paid	0.0	0.0	0.0	0.0
Intra-entity dividends paid	0.0	0.0	0.0	0.0
Proceeds from issuance of common shares		1.4	0.0	8.8
Excess tax benefit from exercise of share awards	0.0	0.0	0.0	0.0
Proceeds from long-term debt		0.0	0.0	398.4
Repayments of long-term debt	0.0	0.0	0.0	0.0
Repayments of Lines of Credit	0.0	0.0	0.0	0.0
Payment of debt issuance costs	0.0	(1.3)	0.0	(7.0)
Proceeds from Lines of Credit	0.0	0.0	0.0	0.0
Payments for Repurchase of Common Stock	0.0	0.0	0.0	0.0
Payments Related to Tax Withholding for Share-based Compensation	0.0	0.0	0.0	0.0
Repayments of Long-term Capital Lease Obligations	0.0	0.0	0.0	0.0
Proceeds from (Repayments of) Short-term Debt	0.0	0.0	0.0	0.0
Intra-entity activity, net	(4.4)	(4.6)	(4.6)	(408.5)
Net cash used in financing activities	(4.4)	(4.5)	(4.6)	(8.3)
Cash and cash equivalents at beginning of period	0.1	0.0	0.1	0.0
Decrease in cash and cash equivalents	0.0	0.0	0.0	0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0	0.0	0.0
Cash and cash equivalents at end of period	0.1	0.0	0.1	0.0
Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	(170.0)	(253.1)	(12.8)	(113.8)
Investing activities
Purchase of property, plant and equipment	(71.7)	(75.1)	(170.3)	(164.7)
Investment in subsidiaries		(1.4)		(8.8)
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 Zale Corporation, net of cash acquired			0.0	(1,431.1)
Net cash used in investing activities	(71.7)	(76.5)	(170.3)	(1,604.6)
Financing activities
Dividends paid	0.0	0.0	0.0	0.0
Intra-entity dividends paid	100.0	(100.0)	100.0	(949.1)
Proceeds from issuance of common shares		0.0	0.0	0.0
Excess tax benefit from exercise of share awards		0.0	5.1	7.7
Proceeds from long-term debt		0.0	0.0	400.0
Repayments of long-term debt	(7.5)	(5.0)	(17.5)	(5.0)
Repayments of Lines of Credit	(30.0)	0.0	(30.0)	0.0
Payment of debt issuance costs	0.0	(0.3)	0.0	(10.7)
Proceeds from Lines of Credit	177.0	145.0	177.0	145.0
Payments for Repurchase of Common Stock	0.0	0.0	0.0	0.0
Payments Related to Tax Withholding for Share-based Compensation	0.0	0.0	0.0	0.0
Repayments of Long-term Capital Lease Obligations	(0.2)	(0.3)	(0.8)	(0.5)
Proceeds from (Repayments of) Short-term Debt	18.5	43.0	(1.5)	20.8
Intra-entity activity, net	102.0	135.0	45.2	1,950.5
Net cash used in financing activities	159.8	217.4	77.5	1,558.7
Cash and cash equivalents at beginning of period	143.0	191.1	166.5	237.0
Decrease in cash and cash equivalents	(81.9)	(112.2)	(105.6)	(159.7)
Effect of exchange rate changes on cash and cash equivalents	(0.1)	(4.8)	0.1	(3.2)
Cash and cash equivalents at end of period	61.0	74.1	61.0	74.1
Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities
Net cash provided by (used in) operating activities	44.4	41.2	98.5	82.9
Investing activities
Purchase of property, plant and equipment	(0.2)		(0.5)	(0.4)
Purchase of available-for-sale securities	(1.9)	(3.0)	(3.8)	(4.2)
Proceeds from available-for-sale securities		1.5	3.6	2.5
Acquisition of Zale Corporation, net of cash acquired				1.9
Net cash used in investing activities	(2.1)	(1.5)	(0.7)	(0.2)
Financing activities
Dividends paid	0.0	0.0	0.0	0.0
Intra-entity dividends paid	0.0		0.0	(0.9)
Proceeds from issuance of common shares				800.0
Excess tax benefit from exercise of share awards	0.0
Proceeds from long-term debt	542.6	493.4	1,738.9	1,424.0
Repayments of long-term debt	(542.6)	(493.4)	(1,738.9)	(824.0)
Repayments of Lines of Credit	0.0	0.0	0.0	0.0
Payment of debt issuance costs	0.0	(0.5)	0.0	(2.8)
Proceeds from Lines of Credit	0.0	0.0	0.0	0.0
Payments for Repurchase of Common Stock	0.0	0.0	0.0	0.0
Payments Related to Tax Withholding for Share-based Compensation	0.0	0.0	0.0	0.0
Repayments of Long-term Capital Lease Obligations	0.0	0.0	0.0	0.0
Proceeds from (Repayments of) Short-term Debt	0.0	0.0	0.0	0.0
Intra-entity activity, net	(45.6)	(55.2)	(109.7)	(1,479.6)
Net cash used in financing activities	(45.6)	(55.7)	(109.7)	(83.3)
Cash and cash equivalents at beginning of period	16.5	22.5	24.9	9.2
Decrease in cash and cash equivalents	(3.3)	(16.0)	(11.9)	(0.6)
Effect of exchange rate changes on cash and cash equivalents	(0.2)	4.1		2.0
Cash and cash equivalents at end of period	$ 13.0	$ 10.6	$ 13.0	$ 10.6