Share Capital (Movements In Shares Issued And Outstanding) (Details) - shares shares in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Common shares issued	490.4	490.4	490.4
Less: Treasury shares for which dividend and voting rights do not apply	(86.6)	(72.9)	(60.5)
Common shares outstanding	403.8	417.5	429.9