Fair Value (Reconciliation of Recurring Fair Value Measurements) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Fair Value Additional Information [Abstract]
Net gains (losses) included in earnings (realized and unrealized) relating to Level 3 assets and liabilities	$ 112	$ (142)	$ 286	$ (95)
Amortization and accretion included in earnings relating to Level 3 assets and liabilities	51	26	137	81
Net unrealized gains (losses) relating to Level 3 assets and liabilities	68	(189)	173	(162)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	10,391	11,740	10,051	12,428
Included in earnings	174	(228)	369	(131)
Included in other comprehensive income	651	(189)	1,200	43
Purchases	223	105	540	454
Sales	(97)	(113)	(523)	(511)
Issuances	32	24	85	94
Settlements	(487)	(686)	(1,294)	(1,724)
Transfers Into Level 3	2		463
Transfers Out of Level 3		(30)	(2)	(30)
Ending Balance	10,889	10,623	10,889	10,623
Unrealized gains or losses on assets held on Consolidated Balance Sheet	89	(265)	186	(209)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	289	444	308	460
Included in Earnings	62	(86)	83	(36)
Sales	1	1	2	9
Settlements	(22)	(167)	(62)	(241)
Transfer into Level 3			1
Transfer out of Level 3			(2)
Ending Balance	330	192	330	192
Unrealized gains or losses on liabilities held on Consolidated Balance Sheet	21	(76)	13	(47)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6,967	7,821	6,729	8,583
Included in earnings	27	(9)	33	(78)
Included in other comprehensive income	651	(189)	1,200	43
Purchases	5	49	63	217
Sales	(8)		(261)	(283)
Settlements	(315)	(378)	(895)	(1,188)
Transfers Into Level 3			458
Transfers Out of Level 3		(26)		(26)
Ending Balance	7,327	7,268	7,327	7,268
Unrealized gains or losses on assets held on Consolidated Balance Sheet	(24)	(35)	(96)	(108)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | 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	5,887	6,454	5,557	7,233
Included in earnings	26	(7)	38	(71)
Included in other comprehensive income	592	(183)	1,078	(1)
Purchases			49	45
Sales			(163)	(280)
Settlements	(285)	(276)	(797)	(938)
Transfers Into Level 3			458
Ending Balance	6,220	5,988	6,220	5,988
Unrealized gains or losses on assets held on Consolidated Balance Sheet	(23)	(30)	(86)	(93)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | 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			2
Settlements			(2)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Available-for-sale Securities [Member] | Asset backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	688	951	787	1,045
Included in earnings	1	(2)	(6)	(5)
Included in other comprehensive income	55	(8)	114	35
Purchases		48		48
Sales			(87)
Settlements	(30)	(93)	(94)	(227)
Ending Balance	714	896	714	896
Unrealized gains or losses on assets held on Consolidated Balance Sheet	(1)	(5)	(9)	(14)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Available-for-sale Securities [Member] | State and Municipal [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	337	341	336	228
Included in other comprehensive income	4		7	3
Purchases				121
Settlements		(9)	(2)	(20)
Ending Balance	341	332	341	332
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Available-for-sale Securities [Member] | Other Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	55	75	49	73
Included in earnings			(1)	(2)
Included in other comprehensive income		2	1	6
Purchases	5	1	14	3
Sales	(8)		(11)	(3)
Settlements				1
Transfers Out of Level 3		(26)		(26)
Ending Balance	52	52	52	52
Unrealized gains or losses on assets held on Consolidated Balance Sheet			(1)	(1)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Available-for-sale Securities [Member] | Corporate Stocks And Other [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance				4
Settlements				(4)
Ending Balance
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	117	60	67	77
Included in earnings	145	89	339	195
Purchases		1	4	4
Settlements	(115)	(62)	(264)	(188)
Transfers Into Level 3			3
Transfers Out of Level 3			(2)
Ending Balance	147	88	147	88
Unrealized gains or losses on assets held on Consolidated Balance Sheet	122	84	291	153
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading Securities - Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	41	56	39	69
Included in earnings	5	1	8	(2)
Settlements	(14)	(6)	(15)	(16)
Transfers Out of Level 3		(4)		(4)
Ending Balance	32	47	32	47
Unrealized gains or losses on assets held on Consolidated Balance Sheet			3	(5)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Residential Mortgage Servicing Rights MSRs [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	581	996	647	1,033
Included in earnings	(45)	(298)	(151)	(369)
Purchases	70		134	48
Issuances	32	24	85	94
Settlements	(44)	(38)	(121)	(122)
Ending Balance	594	684	594	684
Unrealized gains or losses on assets held on Consolidated Balance Sheet	(44)	(294)	(140)	(360)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Assets Held-for-sale [Member] | Commercial Mortgages [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	837	856	843	877
Included in earnings	(2)	4	(4)	4
Sales	(26)		(30)	(13)
Settlements	2	(29)	2	(37)
Ending Balance	811	831	811	831
Unrealized gains or losses on assets held on Consolidated Balance Sheet	(4)	4	(7)	3
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Equity Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,634	1,513	1,504	1,384
Included in earnings	34	65	144	169
Purchases	147	55	336	182
Sales	(63)	(113)	(232)	(215)
Ending Balance	1,752	1,520	1,752	1,520
Unrealized gains or losses on assets held on Consolidated Balance Sheet	29	56	135	158
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Equity Investments [Member] | Direct Investments Equity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	957	849	856	749
Included in earnings	26	39	68	73
Purchases	135	40	294	142
Sales	(24)	(67)	(124)	(103)
Ending Balance	1,094	861	1,094	861
Unrealized gains or losses on assets held on Consolidated Balance Sheet	21	29	62	60
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Equity Investments [Member] | Indirect Investments Equity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	677	664	648	635
Included in earnings	8	26	76	96
Purchases	12	15	42	40
Sales	(39)	(46)	(108)	(112)
Ending Balance	658	659	658	659
Unrealized gains or losses on assets held on Consolidated Balance Sheet	8	27	73	98
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	7	4	5	2
Purchases	1		3	2
Settlements	(1)		(1)
Ending Balance	7	4	7	4
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	207	434	217	403
Included in earnings	10	(80)		(50)
Purchases				1
Settlements		(173)		(173)
Transfers Into Level 3	2		2
Ending Balance	219	181	219	181
Unrealized gains or losses on assets held on Consolidated Balance Sheet	10	(80)		(50)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Assets [Member] | Black Rock Series C Preferred Stock [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	200	426	210	396
Included in earnings	10	(80)		(50)
Settlements		(172)		(172)
Ending Balance	210	174	210	174
Unrealized gains or losses on assets held on Consolidated Balance Sheet	10	(80)		(50)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Assets [Member] | Other Assets Fair Value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	7	8	7	7
Purchases				1
Settlements		(1)		(1)
Transfers Into Level 3	2		2
Ending Balance	$ 9	$ 7	$ 9	$ 7