Shareholders' equity - Share Repurchase (Details) - 2013 Program - USD ($) $ / shares in Units, $ in Millions		9 Months Ended
		Oct. 31, 2015	Nov. 01, 2014	Jun. 14, 2013
Class of Stock [Line Items]
Amount authorized	[1]			$ 350.0
Shares repurchased (shares)		868,325	288,393
Amount repurchased		$ 111.9	$ 29.8
Average repurchase price per share (usd per share)		$ 128.91	$ 103.37
Remaining authorized repurchase amount		$ 153.7

[1] On June 14, 2013, the Board of Directors authorized the repurchase of up to $350 million of Signet’s common shares (the “2013 Program”). The 2013 Program may be suspended or discontinued at any time without notice. The 2013 Program had $153.7 million remaining as of October 31, 2015.