Stockholders' Equity Stockholders' Equity (Income attributable to participating securities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stockholders' Equity [Line Items]
Participating Securities, Distributed and Undistributed Earnings	$ 39	$ 36	$ 31
Continuing Operations [Member]
Stockholders' Equity [Line Items]
Participating Securities, Distributed and Undistributed Earnings	38	36	31
Discontinued Operations [Member]
Stockholders' Equity [Line Items]
Participating Securities, Distributed and Undistributed Earnings	1	0	0
Maximum [Member] | Discontinued Operations [Member]
Stockholders' Equity [Line Items]
Participating Securities, Distributed and Undistributed Earnings		$ (1)	$ 1