Quarterly Data (Unaudited) - Quarterly Per Share Information (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Data [Abstract]
Weighted average common shares outstanding—basic	861	861	860	858	856	857	856	855	860	856	816
Earnings Per Share, Basic	$ 0.02	$ 1.15	$ 0.61	$ 0.10	$ 0.60	$ 0.86	$ 0.57	$ (0.01)
Weighted average common shares outstanding—diluted	868	863	864	861	860	860	860	855	864	860	819
Earnings Per Share, Diluted	$ 0.02	$ 1.15	$ 0.60	$ 0.10	$ 0.59	$ 0.86	$ 0.57	$ (0.01)	$ 1.88	$ 2.00	$ 1.42