Share Capital (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Class of Stock [Line Items]
Treasury stock shares	90.0	90.0		81.3
Treasury shares held, as unvested restricted stock awards	9.5	9.5		8.4
Common shares market price (per share)		$ 25.54
Treasury shares market value		$ 2,300.0
Treasury stock acquired (shares)	4.7
Purchase of shares	$ 120.0	394.0	$ 225.0
Accelerated Share Repurchases, Settlement (Payment) or Receipt	$ (150.0)	$ (150.0)