Accumulated Other Comprehensive Income/(Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 944
Net change	3,303	1,067	610
Net change	(69)	(279)	269
Net change	69	(155)	25
Net change	(145)	(690)	332
Net change	3,158	(57)	1,236
Ending Balance	4,102	944
Accumulated other comprehensive income (loss) - supplemental information
After-tax unrealized losses not related to credit on debt securities		(56)	(81)
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Unrealized gains on AFS securities	3,303	1,067	610
Net change after tax	(69)	(279)	269
Net change	69	(155)	25
Net change after tax	(145)	(690)	332
Net change	3,158	(57)	1,236
Total other comprehensive income/(loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	944	1,001	(91)
Net change	3,158	(57)	1,236
Ending Balance	4,102	944	1,001
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Total Other comprehensive income/(loss) before tax	5,147	(58)	1,972
Total Other comprehensive income/(loss) tax effect	(1,989)	1	(736)
Net change	3,158	(57)	1,236
Total other comprehensive income/(loss) | Adjustments for New Accounting Pronouncement [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Cumulative Effect of Prospective Application of New Accounting Principle	0	0	(144)
Total other comprehensive income/(loss) | Impact of new accounting guidance for consolidation of VIEs [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Net change		129
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Unrealized gains on AFS securities		129
Total other comprehensive income/(loss) | Accounting Standards Update 2010-11 [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Net change		15
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Unrealized gains on AFS securities		15
Unrealized gains/(losses) on AFS securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	3,565	2,498	2,032
Net change	3,303	1,067	610
Ending Balance	6,868	3,565	2,498
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net unrealized gains/(losses) arising during the period before tax	7,521	3,361	3,982
Net unrealized gains/(losses) arising during the period tax effect	(2,930)	(1,322)	(1,540)
Net unrealized gains/(losses) arising during the period after tax	4,591	2,039	2,442
Reclassification adjustment for realized (gains)/losses included in net income before tax	(2,110)	(1,593)	(2,982)
Reclassification adjustment for realized (gains)/losses included in net income tax effect	822	621	1,150
Reclassification adjustment for realized (gains)/losses included in net income after tax	(1,288)	(972)	(1,832)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment Including OTTI, Before Tax	5,411	1,768	1,000
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment Including OTTI, Tax	(2,108)	(701)	(390)
Unrealized gains on AFS securities	3,303	1,067	610
Unrealized gains/(losses) on AFS securities | Adjustments for New Accounting Pronouncement [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Net change			(144)
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Unrealized gains on AFS securities			(144)
Translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(26)	253	(16)
Net change	(69)	(279)	269
Ending Balance	(95)	(26)	253
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Translation before tax	(26)	(672)	402
Translation tax effect	8	255	(139)
Translation after tax	(18)	(417)	263
Hedges before tax	(82)	226	11
Hedges tax effect	31	(88)	(5)
Hedges after tax	(51)	138	6
Net change before tax	(108)	(446)	413
Net change tax effect	39	167	(144)
Net change after tax	(69)	(279)	269
Translation adjustments | Adjustments for New Accounting Pronouncement [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Net change			0
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net change after tax			0
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	51	206	181
Net change	69	(155)	25
Ending Balance	120	51	206
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net unrealized gains/(losses) arising during the period before tax	141	50	247
Net unrealized gains/(losses) arising during the period tax effect	(55)	(19)	(96)
Net unrealized gains/(losses) arising during the period after tax	86	31	151
Reclassification adjustment for realized (gains)/losses included in net income before tax	(28)	(301)	(206)
Reclassification adjustment for realized (gains)/losses included in net income tax effect	11	115	80
Reclassification adjustment for realized (gains)/losses included in net income after tax	(17)	(186)	(126)
Net change before tax	113	(251)	41
Net change tax effect	(44)	96	(16)
Net change	69	(155)	25
Cash flow hedges | Adjustments for New Accounting Pronouncement [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Net change			0
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net change			0
Net loss and prior service costs/(credit) of defined benefit pension and OPEB plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(2,646)	(1,956)	(2,288)
Net change	(145)	(690)	332
Ending Balance	(2,791)	(2,646)	(1,956)
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Arising During Period, before Tax	6	0	10
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Benefit Plan Improvement, Tax Effect	(2)	0	(4)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Costs Arising During Period, Net of Tax	4	0	6
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(537)	(1,290)	262
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized (Gain) Loss Arising During Period, Tax	228	502	(84)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax	(309)	(788)	178
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	324	214	280
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Tax	(126)	(83)	(112)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Net of Tax	198	131	168
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax	(41)	(52)	(57)
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Tax	16	20	22
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Net of Tax	(25)	(32)	(35)
Other Comprehensive Income (Loss), Finalization of Pension and Non-Pension Postretirement Plan Valuation, before Tax	0	0	1
Other Comprehensive Income (Loss), Finalization of Pension and Non-Pension Postretirement Plan Valuation, Tax		0	0
Other Comprehensive Income (Loss), Finalization of Pension and Non-Pension Postretirement Plan Valuation, Net of Tax	0	0	1
Other Comprehensive Income (Loss), Foreign Currency Exchange Rate and Other Changes, before Tax	(21)	(1)	22
Other Comprehensive Income (Loss) Foreign Currency Exchange Rate and Other Changes , Tax	8	0	(8)
Other Comprehensive Income (Loss), Foreign Currency Exchange Rate and Other Changes, net of Tax	(13)	(1)	14
Total recognized in other comprehensive income	(269)	(1,129)	518
Net change tax effect	124	439	(186)
Net change after tax	(145)	(690)	332
Net loss and prior service costs/(credit) of defined benefit pension and OPEB plans | Adjustments for New Accounting Pronouncement [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Net change			0
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net change after tax			$ 0