Shareholders' equity - Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								9 Months Ended
	Oct. 31, 2015	Aug. 01, 2015	May. 02, 2015	[1]	Nov. 01, 2014	Aug. 02, 2014	May. 03, 2014	[1]	Oct. 31, 2015	Nov. 01, 2014
Equity [Abstract]
Common Stock, Dividends, Per Share, Declared	$ 0.22	$ 0.22	$ 0.22		$ 0.18	$ 0.18	$ 0.18		$ 0.66	$ 0.54
Dividends, Common Stock	$ 17.5	$ 17.6	$ 17.6		$ 14.4	$ 14.4	$ 14.4		$ 52.7
Dividends Payable	$ 17.5				$ 14.4				$ 17.5	$ 14.4

[1] Signet’s dividend policy results in the dividend payment date being a quarter in arrears from the declaration date. As a result,