Accumulated Other Comprehensive Income/(Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ 944
Ending Balance	2,645		944
Total other comprehensive income/(loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	944	1,001
Net change	1,701	(289)
Ending Balance	2,645	712
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Total Other comprehensive income/(loss) before tax	2,770	(486)
Total Other comprehensive income/(loss) tax effect	(1,069)	197
Unrealized gains/(losses) on AFS securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	3,565	2,498
Ending Balance	5,139	2,247
Accumulated other comprehensive income (loss) - supplemental information
After-tax unrealized losses not related to credit on debt securities	(48)	(65)	(56)	(81)
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net unrealized gains/(losses) arising during the period before tax	3,118	(315)
Net unrealized gains/(losses) arising during the period tax effect	(1,217)	124
Net unrealized gains/(losses) arising during the period after tax	1,901	(191)
Reclassification adjustment for realized (gains)/losses included in net income before tax	(536)	(97)
Reclassification adjustment for realized (gains)/losses included in net income tax effect	209	37
Reclassification adjustment for realized (gains)/losses included in net income after tax	(327)	(60)
Net change before tax	2,582	(412)
Net change tax effect	(1,008)	161
Net change after tax	1,574	(251)
Translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(26)	253
Ending Balance	101	277
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Translation before tax	460	418
Translation tax effect	(169)	(156)
Translation after tax	291	262
Hedges - gain/(loss) before tax	(267)	(390)
Hedges - gains/(losses) tax effect during period	103	152
Hedges - gains/(losses) after tax	(164)	(238)
Net change before tax	193	28
Net change tax effect	(66)	(4)
Net change after tax	127	24
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	51	206
Ending Balance	16	127
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net unrealized gains/(losses) before tax	(41)	(13)
Net unrealized gains/(losses) arising during the period, tax	17	5
Net unrealized gains/(losses), Net of Tax	(24)	(8)
Reclassification adjustment for realized (gains)/losses included in net income, before tax	(20)	(116)
Reclassification adjustment for realized (gains)/losses included in net income, tax	(9)	(45)
Reclassification adjustment for realized (gains)/losses included in net income, net of tax	11	71
Net change before tax	(61)	(129)
Net change tax effect	26	50
Net change after tax	(35)	(79)
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)
Ending Balance	(2,611)	(1,939)
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net gains/(losses), pension and OPEB, arising during period, before tax	2	8
Net gains/(losses), pension and OPEB, arising during period, tax	0	(2)
Net gains/(losses), pension and OPEB, arising during period, net of tax	2	6
Reclassification adjustments included in net income, prior service costs/(credits), before tax	(11)	(12)
Reclassification adjustments included in net income, prior service costs/(credits), tax	4	5
Reclassification adjustments included in net income, prior service costs/(credits), net of tax	(7)	(7)
Reclassification adjustments included in net income, amortization of net loss, before tax	83	53
Reclassification adjustments included in net income, amortization of net loss, tax effect	(32)	(21)
Reclassification adjustments included in net income, amortization of net loss, net of tax	51	32
Other Comprehensive Income (Loss), Foreign Currency Exchange Rate and Other Changes, before Tax	(11)	(14)
Other Comprehensive Income (Loss) Foreign Currency Exchange Rate and Other Changes , Tax	7	8
Other Comprehensive Income (Loss), Foreign Currency Exchange Rate and Other Changes, before Tax	(18)	(22)
Net change before tax	56	27
Net change tax effect	(21)	(10)
Net change after tax	35	17
Foreign exchange contract
Changes of the components of Accumulated Other Comprehensive Income (Loss)
Net unrealized gains/(losses) before tax	79	18
Reclassification adjustment for realized (gains)/losses included in net income, before tax	1	(22)
Net change before tax	$ 80	$ (4)