(Loss) Earnings Per Common Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
(Loss) Income (Numerator):
Net (loss) income									$ (239)		$ 777		$ 573
Earnings applicable to non-vested restricted stock									0		(1)		(2)
Net (loss) income as adjusted for purposes of computing basic earnings per common share									(239)		776		571
Net (loss) income as adjusted for purposes of computing diluted earnings per common share									$ (239)		$ 776		$ 571
Weighted average number of shares:
Outstanding during period (in shares)									604,404,000		622,139,000		534,320,000
Non-vested restricted stock (in shares)									(3,512,000)		(2,796,000)		(2,209,000)
Non-vested restricted stock units (in shares)									0		862,000		669,000
Weighted average shares outstanding for computing basic earnings per common share (in shares)									600,892,000		620,205,000		532,780,000
Incremental common shares attributable to dilutive securities:
Shares issuable under convertible securities (in shares)									0		12,000		13,000
Shares issuable under incentive compensation plans (in shares)									0		2,068,000		1,328,000
Number of shares as adjusted for purposes of computing diluted earnings per common share (in shares)									600,892,000		622,285,000		534,121,000
Basic earnings per common share (in dollars per share)	$ 0.41	$ (1.76)	$ 0.45	$ 0.48	$ 0.37	$ 0.43	$ 0.12	$ 0.32	$ (0.40)		$ 1.25		$ 1.07
Diluted earnings per common share (in dollars per share)	$ 0.41	$ (1.76)	$ 0.44	$ 0.48	$ 0.37	$ 0.43	$ 0.12	$ 0.32	$ (0.40)	[1]	$ 1.25	[1]	$ 1.07	[1]
Number of shares of common stock excluded from the computation of diluted earnings per share									1,300,000
Stock option awards
Incremental common shares attributable to dilutive securities:
Number of shares of common stock excluded from the computation of diluted earnings per share									2,700,000		2,200,000		2,400,000

[1] For the year ended December 31, 2013, we excluded from the calculation of diluted loss per share 1.3 million shares potentially issuable under incentive compensation plans or convertible securities, as their effect, if included, would have been anti-dilutive.