Earnings Per Share Earnings Per Share - Reconciliation of Basic and Diluted EPS Table (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share Disclosure [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	$ 474	$ (940)	$ 1,570
Basic	653	643	637
Basic	$ 0.73	$ (1.46)	$ 2.47
Diluted	$ 0.73	$ (1.46)	$ 2.32
Net Income (Loss) Attributable to Parent	724	(769)	1,742
Weighted Average Number of Shares Outstanding, Diluted	653	643	752
Restricted stock
Earnings Per Share Disclosure [Line Items]
Weighted Average Number Diluted Shares Outstanding Adjustment			9
Amount of Dilutive Securities, Restrictive Stock Units			0
Stock Options
Earnings Per Share Disclosure [Line Items]
Weighted Average Number Diluted Shares Outstanding Adjustment			1
Amount of Dilutive Securities, Stock Options			0
5.75% Cumulative Convertible Preferred Stock
Earnings Per Share Disclosure [Line Items]
Effect Of Dilutive Securities On Net Income Loss			86
5.75% Cumulative Convertible Preferred Stock | Convertible Debt Securities [Member]
Earnings Per Share Disclosure [Line Items]
Weighted Average Number Diluted Shares Outstanding Adjustment			55
5.75% Cumulative Convertible Preferred Stock Series A | Convertible Debt Securities [Member]
Earnings Per Share Disclosure [Line Items]
Effect Of Dilutive Securities On Net Income Loss			63
Weighted Average Number Diluted Shares Outstanding Adjustment			39
5.0% Cumulative Convertible Preferred Stock Series Two Thousand And Five B [Member] | Convertible Debt Securities [Member]
Earnings Per Share Disclosure [Line Items]
Effect Of Dilutive Securities On Net Income Loss			11
Weighted Average Number Diluted Shares Outstanding Adjustment			5
4.50% Cumulative Convertible Preferred Stock [Member] | Convertible Debt Securities [Member]
Earnings Per Share Disclosure [Line Items]
Effect Of Dilutive Securities On Net Income Loss			$ 12
Weighted Average Number Diluted Shares Outstanding Adjustment			6