Earnings 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
Earnings Per Share [Abstract]
Participating Securities, Distributed and Undistributed Earnings	$ 4				$ 13
Antidilutive securities excluded from computation of earnings per share	4.1		8.2		2.8		5.7
Numerator for earnings per share calculations:
Income from continuing operations attributable to common stockholders	$ 944	[1]	$ 1,255	[1]	$ 3,310	[1]	$ 3,334	[1]
Denominators for earnings per share calculations:
Weighted averages shares outstanding, basic (in shares)	1,157		1,218		1,167		1,226
Effect of dilutive securities
Stock options (in shares)	7		8		8		8
Weighted averages shares outstanding, diluted (in shares)	1,164		1,226		1,175		1,234
Earnings Per Share, Basic [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.82		$ 1.03		$ 2.84		$ 2.72
Diluted earnings per share:
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.81		$ 1.02		$ 2.82		$ 2.70

[1] Comprised of income from continuing operations less amounts allocable to participating securities of $4 million and $13 million for the three and nine months ended September 30, 2014.