Share Capital (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Class of Stock [Line Items]
Treasury stock shares	91.3		81.3
Treasury shares held, as unvested restricted stock awards	9.4		8.4
Common shares market price (per share)	$ 31.27
Treasury shares market value	$ 2,900.0
Purchase of shares	$ 424.9	$ 403.6