Other Comprehensive Income, Cumulative OCI Balances (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investment securities:
Cumulative other comprehensive income, Investment securities, beginning of period	$ 4,784	$ 3,746	$ 4,926	$ 2,338
Net unrealized gains (losses) arising during the period	(1,291)	1,249	(945)	2,981
Amounts reclassified from accumulated other comprehensive income	(136)	(94)	(323)	(339)
Net change, Net of tax	(1,427)	1,155	(1,268)	2,642
Less: Other comprehensive income from noncontrolling interests	(152)	(124)	149	(45)
Cumulative other comprehensive income, Investment securities, end of period	3,509	5,025	3,509	5,025
Derivatives and hedging activities:
Cumulative other comprehensive income, Derivatives and hedging activities, beginning of period	781	41	333	80
Net unrealized gains (losses) arising during the period	(304)	132	289	159
Amounts reclassified from accumulated other comprehensive income	(167)	(71)	(312)	(137)
Net change, Net of tax	(471)	61	(23)	22
Less: Other comprehensive income from noncontrolling interests	0	0	0	0
Cumulative other comprehensive income, Derivatives and hedging activities, end of period	310	102	310	102
Defined benefit plans adjustments:
Cumulative other comprehensive loss, Defined benefit plans adjustment, beginning of period	(1,684)	(1,042)	(1,703)	(1,053)
Net unrealized gains (losses) arising during the period	0	(7)	(7)	(7)
Amounts reclassified from accumulated other comprehensive income	19	12	45	23
Net change, Net of tax	19	5	38	16
Less: Other comprehensive income from noncontrolling interests	0	0	0	0
Cumulative other comprehensive loss, Defined benefit plans adjustment, end of period	(1,665)	(1,037)	(1,665)	(1,037)
Foreign currency translation adjustments:
Cumulative other comprehensive income (loss), Foreign currency translation adjustments, beginning of period	(104)	7	(38)	21
Net unrealized gains (losses) arising during the period	16	20	(50)	0
Amounts reclassified from accumulated other comprehensive income	0	0	0	6
Net change, Net of tax	16	20	(50)	6
Less: Other comprehensive income from noncontrolling interests	(2)	0	(2)	0
Cumulative other comprehensive income (loss), Foreign currency translation adjustments, end of period	(86)	27	(86)	27
Cumulative other comprehensive income, beginning of period	3,777	2,752	3,518	1,386
Net unrealized gains (losses) arising during the period	(1,579)	1,394	(713)	3,133
Amounts reclassified from accumulated other comprehensive income	(284)	(153)	(590)	(447)
Other comprehensive income (loss), net of tax	(1,863)	1,241	(1,303)	2,686
Less: Other comprehensive income (loss) from noncontrolling interests, net of tax	(154)	(124)	147	(45)
Cumulative other comprehensive income, end of period	$ 2,068	$ 4,117	$ 2,068	$ 4,117