Earnings Per Share (Details) (USD $) In Millions, except Per 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
Basic Earnings per Share
Net income (loss) attributable to stockholders	$ 1,040	$ 1,717	$ 1,414	$ 1,175	$ 1,194	$ 1,833	$ 1,846	$ 1,315	$ 5,346	$ 6,188	$ 9,190
Preferred Stock Dividends and Charge Related to Purchase of Preferred Stock									(1,576)	(859)	(859)
Net income (loss) attributable to common stockholders									3,770	4,859	7,585
Weighted-average common shares outstanding - basic									1,393	1,566	1,536
Basic earnings per common share	$ 0.64	$ 0.50	$ 0.87	$ 0.63	$ 0.58	$ 0.94	$ 0.95	$ 0.64	$ 2.71	$ 3.10	$ 4.94
Earnings Per Share, Diluted [Abstract]
Net income (loss) attributable to stockholders	1,040	1,717	1,414	1,175	1,194	1,833	1,846	1,315	5,346	6,188	9,190
Preferred Stock Dividends and Charge Related to Purchase of Preferred Stock									(1,576)	(859)	(859)
Net income (loss) attibutable to common stockholders									3,988	4,887	7,638
Weighted Average Common Shares Outstanding - Diluted [Abstract]
Weighted-average common shares outstanding									1,393	1,566	1,536
Dilutive effect of warrants									146	104	130
Dilutive effect of restricted stock units									3	5	2
Weighted-average common shares outstanding - diluted									1,676	1,675	1,668
Diluted earnings (loss) per share	$ 0.57	$ 0.45	$ 0.75	$ 0.58	$ 0.54	$ 0.89	$ 0.90	$ 0.60	$ 2.38	$ 2.92	$ 4.58
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Lower share price boundary for two class method									$ 33.00	$ 33.00	$ 33.00
Higher share price boundary for two class method									$ 39.60	$ 39.60	$ 39.60
Common Stock Trading Days									40 days	40 days	40 days
Assumed change of method impact to earnings per share									$ 0.13
Warrants excluded from computation of diluted EPS (shares)									46	46	46
Series A Preferred Stock [Member]
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Earned but undeclared dividends on preferred stock									15	26	26
Series B Preferred Stock [Member]
Basic Earnings per Share
Less: undistributed earnings allocated to Series B preferred stock participating security									0	(470)	(746)
Earnings Per Share, Diluted [Abstract]
Add: preferred dividends to holders of Series B Preferred Stock									218	0	0
Less: undistributed earnings allocated to Series B Preferred Stock participating security									0	(442)	(693)
Weighted Average Common Shares Outstanding - Diluted [Abstract]
Dilutive effect of conversion of Series B Preferred Stock									134	0	0
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Earned but undeclared dividends on preferred stock										$ 20	$ 20
Preferred Stock Assumed Converted										152	152