Shareholders' equity - Share Repurchase (Details) - 2013 Program - USD ($) $ / shares in Units, $ in Millions		6 Months Ended
		Aug. 01, 2015	Aug. 02, 2014	Jun. 14, 2013
Class of Stock [Line Items]
Amount authorized	[1]			$ 350.0
Shares repurchased (shares)		628,955	220,132
Amount repurchased		$ 81.9	$ 22.4
Average repurchase price per share (usd per share)		$ 130.27	$ 101.57
Remaining authorized repurchase amount		$ 183.7

[1] On June 14, 2013, the Board 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 $183.7 million remaining as of August 1, 2015.