Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Net income (loss)	$ 685	$ (168)	$ 692	$ (44)
Basic weighted average shares outstanding	850	845	849	844
Dilutive effect of share based awards	9	0	7	0
Diluted weighted average shares outstanding	859	845	856	844
Basic earnings (loss) per share	$ 0.81	$ (0.20)	$ 0.81	$ (0.05)
Diluted earnings (loss) per share	$ 0.80	$ (0.20)	$ 0.81	$ (0.05)
Antidilutive common stock equivalents excluded from diluted earnings per share	12	23	13	23