Fair Value (Reconciliation of Recurring Fair Value Measurements) (Details) - Fair Value, Measurements, Recurring [Member] - Level 3 [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 8,029	$ 9,636	$ 8,606	$ 9,788
Included in earnings	(35)	255	(197)	351
Included in other comprehensive income	22	(3)	(38)	(14)
Purchases	187	213	303	392
Sales	(1,019)	(1,303)	(1,696)	(2,407)
Issuances	1,155	1,049	1,822	2,163
Settlements	(371)	(541)	(816)	(947)
Transfers Into Level 3	236	7	238	13
Transfers Out of Level 3	(16)	(19)	(34)	(45)
Ending Balance	8,188	9,294	8,188	9,294
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	(63)	203	(268)	204
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	355	710	495	716
Included in earnings	63	(12)	70	30
Sales	1	1	3	1
Issuances	51	21	112	46
Settlements	(64)	(47)	(274)	(120)
Ending Balance	406	673	406	673
Unrealized gains or (losses) on liabilities held on Consolidated Balance Sheet	65	(25)	69	(17)
Fair Value Additional Information [Abstract]
Net gains (losses) included in earnings (realized and unrealized) relating to Level 3 assets and liabilities	(98)	267	(267)	321
Net unrealized gains (losses) relating to Level 3 assets and liabilities	(128)	228	(337)	221
Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	4,305	5,338	4,535	5,525
Included in earnings	14	36	39	75
Included in other comprehensive income	22	(3)	(36)	(14)
Purchases	7		9	3
Sales	(62)		(64)
Settlements	(245)	(367)	(442)	(585)
Ending Balance	4,041	5,004	4,041	5,004
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet			(1)	(1)
Available-for-sale Securities [Member] | Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	3,810	4,624	4,008	4,798
Included in earnings	11	30	33	55
Included in other comprehensive income	17	(8)	(28)	(22)
Sales	(60)		(60)
Settlements	(221)	(222)	(396)	(407)
Ending Balance	3,557	4,424	3,557	4,424
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet			(1)	(1)
Available-for-sale Securities [Member] | Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Non-agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Included in earnings		1		8
Settlements		(1)		(8)
Available-for-sale Securities [Member] | Asset backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	451	548	482	563
Included in earnings	3	5	6	11
Included in other comprehensive income	4	5	(8)	9
Settlements	(22)	(27)	(44)	(52)
Ending Balance	436	531	436	531
Available-for-sale Securities [Member] | State and Municipal [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	14	133	15	134
Included in other comprehensive income	1			(1)
Settlements		(117)		(117)
Ending Balance	15	16	15	16
Available-for-sale Securities [Member] | Other debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	30	33	30	30
Included in earnings				1
Purchases	7		9	3
Sales	(2)		(4)
Settlements	(2)		(2)	(1)
Ending Balance	33	33	33	33
Financial Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	41	54	31	42
Included in earnings	35	16	69	87
Purchases	1		1	1
Settlements	(26)	(34)	(50)	(94)
Ending Balance	51	36	51	36
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	32	33	65	76
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	333	529	473	526
Included in earnings	62	(15)	69	26
Sales	1	1	3	1
Settlements	(11)	(17)	(160)	(55)
Ending Balance	385	498	385	498
Unrealized gains or (losses) on liabilities held on Consolidated Balance Sheet	65	(25)	69	(17)
Loans Held For Sale [Member] | Residential Mortgage [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	4	7	5	6
Purchases	3	11	6	17
Sales		(2)	(1)	(2)
Settlements		(1)		(1)
Transfers Into Level 3	3	1	5	2
Transfers Out of Level 3	(4)	(6)	(9)	(12)
Ending Balance	6	10	6	10
Loans Held For Sale [Member] | Commercial Mortgage [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	655	975	641	893
Included in earnings	21	23	37	44
Sales	(805)	(1,215)	(1,454)	(2,235)
Issuances	1,129	1,008	1,776	2,091
Settlements	(19)	(34)	(19)	(36)
Ending Balance	981	757	981	757
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	12		13	2
Trading Securities - Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	2	3	3	32
Settlements			(1)	(29)
Ending Balance	2	3	2	3
Mortgage Servicing Rights [Member] | Residential Mortgage [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	863	839	1,063	845
Included in earnings	(113)	135	(339)	68
Purchases	53	67	105	150
Issuances	12	21	23	38
Settlements	(41)	(47)	(78)	(86)
Ending Balance	774	1,015	774	1,015
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	(113)	134	(336)	72
Mortgage Servicing Rights [Member] | Commercial Mortgage [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	460	494	526	506
Included in earnings	(9)	34	(64)	18
Purchases	6	17	9	28
Issuances	14	20	23	34
Settlements	(23)	(22)	(46)	(43)
Ending Balance	448	543	448	543
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	(9)	34	(64)	18
Equity Investments [Member] | Direct equity investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,156	1,149	1,098	1,152
Included in earnings	15	27	66	56
Purchases	95	95	118	138
Sales	(146)	(80)	(162)	(155)
Ending Balance	1,120	1,191	1,120	1,191
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	13	22	63	40
Equity Investments [Member] | Indirect Equity Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers Into Level 3	233		233
Ending Balance	233		233
Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	329	383	340	397
Included in earnings	1	5	3	15
Purchases	22	23	55	55
Sales	(6)	(4)	(14)	(8)
Settlements	(17)	(35)	(42)	(72)
Transfers Into Level 3		6		11
Transfers Out of Level 3	(12)	(13)	(25)	(33)
Ending Balance	317	365	317	365
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	1	1	2	9
Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	214	394	364	390
Included in earnings	1	(21)	(8)	(12)
Included in other comprehensive income			(2)
Sales		(2)	(1)	(7)
Settlements		(1)	(138)	(1)
Ending Balance	215	370	215	370
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	1	(21)	(10)	(12)
Other Assets [Member] | BlackRock Series C Preferred Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	208	384	357	375
Included in earnings	1	(21)	(10)	(12)
Settlements			(138)
Ending Balance	209	363	209	363
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet	1	(21)	(10)	(12)
Other Assets [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6	10	7	15
Included in earnings			2
Included in other comprehensive income			(2)
Sales		(2)	(1)	(7)
Settlements		(1)		(1)
Ending Balance	6	7	6	7
Other Borrowed Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	8	171	12	181
Included in earnings		3		3
Issuances	17	21	40	46
Settlements	(17)	(30)	(44)	(65)
Ending Balance	8	165	8	165
Other Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	14	10	10	9
Included in earnings	1		1	1
Issuances	34		72
Settlements	(36)		(70)
Ending Balance	$ 13	$ 10	$ 13	$ 10