Earnings Per Common Share (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Income (Numerator):
Net income	$ 102	$ 238	$ 313	$ 491
Earnings applicable to nonvested restricted stock			(1)	(2)
Net income applicable to common stock for computing basic earnings per common share	102	238	312	489
Net income as adjusted for purposes of computing diluted earnings per common share	$ 102	$ 238	$ 312	$ 489
Weighted average number of shares:
Outstanding during period (in shares)	600,699	300,704	453,042	300,125
Nonvested restricted stock (in shares)	(1,922)	(1,591)	(1,965)	(1,470)
Nonvested restricted stock units (in shares)	107	945	281	1,081
Weighted average number of shares outstanding during period for computing basic earnings per common share (in shares)	598,884	300,058	451,358	299,736
Incremental common shares attributable to dilutive securities:
Shares issuable under convertible securities (in shares)	13	13	13	13
Shares issuable under incentive compensation plans (in shares)	1,362	534	998	552
Number of shares as adjusted for purposes of computing diluted earnings per common share (in shares)	600,259	300,605	452,369	300,301
Basic earnings per common share (in dollars per share)	$ 0.17	$ 0.79	$ 0.69	$ 1.63
Diluted earnings per common share (in dollars per share)	$ 0.17	$ 0.79	$ 0.69	$ 1.63
Stock option awards
Antidilutive securities excluded from computation of earnings per share
Number of shares of common stock excluded from the computation of diluted earnings per share (in shares)	2,541	3,427	2,100	3,495