Earnings Per Share Earnings Per Share - Reconciliation of Basic and Diluted EPS Table (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share Adjustments, Basic and Diluted [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	$ (4,151)	$ 145	$ (7,933)	$ 518
Weighted Average Number of Shares Outstanding, Basic	662	659	662	658
Earnings Per Share, Basic	$ (6.27)	$ 0.22	$ (11.99)	$ 0.79
Net Income (Loss) Available to Common Stockholders, Diluted				$ 593
Weighted Average Number of Shares Outstanding, Diluted	662	659	662	760
Earnings Per Share, Diluted	$ (6.27)	$ 0.22	$ (11.99)	$ 0.78
Employee Stock Option [Member]
Earnings Per Share Adjustments, Basic and Diluted [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities				$ 0
Weighted Average Number Diluted Shares Outstanding Adjustment				1
5.75% Cumulative Convertible Preferred Stock [Member]
Earnings Per Share Adjustments, Basic and Diluted [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities				$ 43
Weighted Average Number Diluted Shares Outstanding Adjustment				59
5.75% Cumulative Convertible Preferred Stock Series A [Member]
Earnings Per Share Adjustments, Basic and Diluted [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities				$ 32
Weighted Average Number Diluted Shares Outstanding Adjustment				42