Earnings Per Share and Equity - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Treasury Stock, Shares held	35,000,000		35,000,000		35,000,000
Treasury Stock, Value	$ 2,327		$ 2,327		$ 2,327
Stock options not included in the calculation of diluted common shares outstanding	4,000,000	2,000,000	2,000,000	1,000,000
Equity Forward Units [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Stock options not included in the calculation of diluted common shares outstanding		2,000,000		1,000,000
Employee Stock Option [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Stock options not included in the calculation of diluted common shares outstanding			14,000,000	16,000,000