Shareholders' Equity - Schedule of weighted average shares outstanding (Details) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Equity [Abstract]
Shares for basic earnings per share	295.5	[1]	311.4	[1]	328.5	[1]
Common stock equivalents	4.1		4.0		4.1
Shares for diluted earnings per share	299.6		315.4		332.6
Number of participating securities	3.0		3.9		4.7

[1] Includes 3.0 million, 3.9 million and 4.7 million shares of participating securities for the years ended December 31, 2014, 2013, and 2012 respectively.