Securities - Amortized Costs, Fair Value (Details 1) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	$ 346,697,000,000	$ 358,940,000,000
Available-for-sale Securities, Gross Unrealized Gains	9,189,000,000	8,804,000,000
Available-for-sale Securities, Gross Unrealized Losses	1,301,000,000	2,963,000,000
Available-for-sale Securities	354,585,000,000	364,781,000,000
Held-to-maturity Securities, Amortized Cost	10,000,000	12,000,000
Held-to-maturity Securities, Gross unrealized gains	1,000,000	1,000,000
Held-to-maturity Securities, Gross unrealized losses	0	0
Held-to-maturity Securities, Fair Value	11,000,000	13,000,000
U.S. government-sponsored enterprise obligations, fair values	80,800,000,000	89,300,000,000
Equity securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	2,591,000,000	2,693,000,000
Available-for-sale Securities, Gross Unrealized Gains	20,000,000	14,000,000
Available-for-sale Securities, Gross Unrealized Losses	1,000,000	2,000,000
Available-for-sale Securities	2,610,000,000	2,705,000,000
Debt Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	344,106,000,000	356,247,000,000
Available-for-sale Securities, Gross Unrealized Gains	9,169,000,000	8,790,000,000
Available-for-sale Securities, Gross Unrealized Losses	1,300,000,000	2,961,000,000
Available-for-sale Securities	351,975,000,000	362,076,000,000
Mortgage-backed securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	174,057,000,000	180,838,000,000
Available-for-sale Securities, Gross Unrealized Gains	6,314,000,000	6,015,000,000
Available-for-sale Securities, Gross Unrealized Losses	476,000,000	960,000,000
Available-for-sale Securities	179,895,000,000	185,893,000,000
US Government Corporations and Agencies Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	90,844,000,000	101,968,000,000
Available-for-sale Securities, Gross Unrealized Gains	5,112,000,000	5,141,000,000
Available-for-sale Securities, Gross Unrealized Losses	1,000,000	2,000,000
Available-for-sale Securities	95,955,000,000	107,107,000,000
Commercial mortgage
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	10,529,000,000	10,632,000,000
Available-for-sale Securities, Gross Unrealized Gains	670,000,000	650,000,000
Available-for-sale Securities, Gross Unrealized Losses	7,000,000	53,000,000
Available-for-sale Securities	11,192,000,000	11,229,000,000
Prime and Alt A [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	2,687,000,000	2,170,000,000
Available-for-sale Securities, Gross Unrealized Gains	58,000,000	54,000,000
Available-for-sale Securities, Gross Unrealized Losses	174,000,000	218,000,000
Available-for-sale Securities	2,571,000,000	2,006,000,000
Subprime [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	262,000,000	1,000,000
Available-for-sale Securities, Gross Unrealized Gains	2,000,000	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities	264,000,000	1,000,000
Non-U.S. [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	69,735,000,000	66,067,000,000
Available-for-sale Securities, Gross Unrealized Gains	472,000,000	170,000,000
Available-for-sale Securities, Gross Unrealized Losses	294,000,000	687,000,000
Available-for-sale Securities	69,913,000,000	65,550,000,000
U.S. Treasury and government agencies [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	11,633,000,000	8,184,000,000
Available-for-sale Securities, Gross Unrealized Gains	111,000,000	169,000,000
Available-for-sale Securities, Gross Unrealized Losses	1,000,000	2,000,000
Available-for-sale Securities	11,743,000,000	8,351,000,000
Obligations of U.S. states and municipalities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	19,111,000,000	15,404,000,000
Available-for-sale Securities, Gross Unrealized Gains	1,526,000,000	1,184,000,000
Available-for-sale Securities, Gross Unrealized Losses	97,000,000	48,000,000
Available-for-sale Securities	20,540,000,000	16,540,000,000
Certificates of Deposit [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	2,989,000,000	3,017,000,000
Available-for-sale Securities, Gross Unrealized Gains	5,000,000	0
Available-for-sale Securities, Gross Unrealized Losses	1,000,000	0
Available-for-sale Securities	2,993,000,000	3,017,000,000
Non-U.S. government debt securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	53,223,000,000	44,944,000,000
Available-for-sale Securities, Gross Unrealized Gains	412,000,000	402,000,000
Available-for-sale Securities, Gross Unrealized Losses	32,000,000	81,000,000
Available-for-sale Securities	53,603,000,000	45,265,000,000
Corporate Debt Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	45,868,000,000	63,607,000,000
Available-for-sale Securities, Gross Unrealized Gains	287,000,000	216,000,000
Available-for-sale Securities, Gross Unrealized Losses	540,000,000	1,647,000,000
Available-for-sale Securities	45,615,000,000	62,176,000,000
Collateralized debt obligations, Asset Backed Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	25,306,000,000	24,474,000,000
Available-for-sale Securities, Gross Unrealized Gains	387,000,000	553,000,000
Available-for-sale Securities, Gross Unrealized Losses	140,000,000	166,000,000
Available-for-sale Securities	25,553,000,000	24,861,000,000
Other, Debt Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	11,919,000,000	15,779,000,000
Available-for-sale Securities, Gross Unrealized Gains	127,000,000	251,000,000
Available-for-sale Securities, Gross Unrealized Losses	13,000,000	57,000,000
Available-for-sale Securities	12,033,000,000	15,973,000,000
Accumulated Other-than-Temporary Impairment [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Gross Unrealized Losses	$ 166,000,000	$ 91,000,000