Net Income per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator:
Net income (loss)	$ 673	$ 689	$ (977)	$ 2,006
Denominator:
Weighted average shares of common stock - basic	1,242	1,295	1,258	1,296
Dilutive effect of equity incentive awards	9	15	0	18
Weighted average shares of common stock - diluted	1,251	1,310	1,258	1,314
Net income (loss) per share:
Basic	$ 0.54	$ 0.53	$ (0.78)	$ 1.55
Diluted	$ 0.54	$ 0.53	$ (0.78)	$ 1.53
Common stock equivalents excluded from income per diluted share because their effect would have been anti-dilutive	8	2	54	2