Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net Income	$ 8,479	$ 1,369	$ 685	$ 7	$ 7	$ 1,047	$ (168)	$ 124	$ 10,540	$ 1,009	$ 854
Basic weighted average shares outstanding									849	845	838
Dilutive effects of share based awards									9	5	6
Diluted weighted average shares outstanding									858	850	844
Basic earnings per share	$ 10.02	$ 1.61	$ 0.81	$ 0.01	$ 0.01	$ 1.24	$ (0.20)	$ 0.15	$ 12.41	$ 1.20	$ 1.02
Diluted earnings per share	$ 9.89	$ 1.59	$ 0.80	$ 0.01	$ 0.01	$ 1.23	$ (0.20)	$ 0.15	$ 12.29	$ 1.19	$ 1.01
Antidilutive common stock equivalents excluded from diluted earnings per share									8	18	17