Investment Securities (Schedule Of Marketable Securities) (Details) (USD $)	Dec. 31, 2012		Dec. 31, 2011
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	$ 108,563,000,000		$ 100,013,000,000
Available For Sale, Gross Unrealized Gains	2,001,000,000		1,471,000,000
Available for sale, Gross Unrealized Losses	882,000,000		1,652,000,000
Available for sale, Fair Value	109,682,000,000		99,832,000,000
Held to maturity, Amortized Cost	11,379,000,000		9,321,000,000
Held to maturity, Gross Unrealized Gains	373,000,000		344,000,000
Held to maturity, Gross Unrealized Losses	91,000,000		303,000,000
Held to maturity, Fair Value	11,661,000,000		9,362,000,000
US Treasury and Federal Agencies, Direct Obligations [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	823,000,000		2,798,000,000
Available For Sale, Gross Unrealized Gains	19,000,000		39,000,000
Available for sale, Gross Unrealized Losses	1,000,000		1,000,000
Available for sale, Fair Value	841,000,000		2,836,000,000
Held to maturity, Amortized Cost	5,000,000,000		0
Held to maturity, Gross Unrealized Gains	0		0
Held to maturity, Gross Unrealized Losses	8,000,000		0
Held to maturity, Fair Value	4,992,000,000		0
US Treasury and Federal Agencies, Mortgage-backed Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	31,640,000,000		29,511,000,000
Available For Sale, Gross Unrealized Gains	598,000,000		538,000,000
Available for sale, Gross Unrealized Losses	26,000,000		28,000,000
Available for sale, Fair Value	32,212,000,000		30,021,000,000
Held to maturity, Amortized Cost	153,000,000		265,000,000
Held to maturity, Gross Unrealized Gains	11,000,000		18,000,000
Held to maturity, Gross Unrealized Losses	0		0
Held to maturity, Fair Value	164,000,000		283,000,000
Asset-backed Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	32,897,000,000		32,905,000,000
Available For Sale, Gross Unrealized Gains	320,000,000		293,000,000
Available for sale, Gross Unrealized Losses	734,000,000		1,297,000,000
Available for sale, Fair Value	32,483,000,000		31,901,000,000
Held to maturity, Amortized Cost	16,000,000		31,000,000
Held to maturity, Gross Unrealized Gains	0		0
Held to maturity, Gross Unrealized Losses	0		2,000,000
Held to maturity, Fair Value	16,000,000		29,000,000
Asset-backed Securities, Student Loans [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	16,829,000,000	[1]	17,187,000,000	[1]
Available For Sale, Gross Unrealized Gains	100,000,000	[1]	69,000,000	[1]
Available for sale, Gross Unrealized Losses	508,000,000	[1]	711,000,000	[1]
Available for sale, Fair Value	16,421,000,000	[1]	16,545,000,000	[1]
Asset-backed Securities, Credit Cards [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	9,928,000,000		10,448,000,000
Available For Sale, Gross Unrealized Gains	61,000,000		53,000,000
Available for sale, Gross Unrealized Losses	3,000,000		14,000,000
Available for sale, Fair Value	9,986,000,000		10,487,000,000
Asset-backed Securities, Sub-prime [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	1,557,000,000		1,849,000,000
Available For Sale, Gross Unrealized Gains	4,000,000		2,000,000
Available for sale, Gross Unrealized Losses	162,000,000		447,000,000
Available for sale, Fair Value	1,399,000,000		1,404,000,000
Asset-backed Securities, Other [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	4,583,000,000		3,421,000,000
Available For Sale, Gross Unrealized Gains	155,000,000		169,000,000
Available for sale, Gross Unrealized Losses	61,000,000		125,000,000
Available for sale, Fair Value	4,677,000,000		3,465,000,000
Non-US Debt Securities, Mortgage-Backed Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	11,119,000,000		10,890,000,000
Available For Sale, Gross Unrealized Gains	313,000,000		92,000,000
Available for sale, Gross Unrealized Losses	27,000,000		107,000,000
Available for sale, Fair Value	11,405,000,000		10,875,000,000
Held to maturity, Amortized Cost	3,122,000,000		4,973,000,000
Held to maturity, Gross Unrealized Gains	85,000,000		87,000,000
Held to maturity, Gross Unrealized Losses	68,000,000		224,000,000
Held to maturity, Fair Value	3,139,000,000		4,836,000,000
Non-US Debt Securities, Asset-Backed Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	6,180,000,000		4,318,000,000
Available For Sale, Gross Unrealized Gains	42,000,000		2,000,000
Available for sale, Gross Unrealized Losses	4,000,000		17,000,000
Available for sale, Fair Value	6,218,000,000		4,303,000,000
Held to maturity, Amortized Cost	434,000,000		436,000,000
Held to maturity, Gross Unrealized Gains	16,000,000		16,000,000
Held to maturity, Gross Unrealized Losses	1,000,000		3,000,000
Held to maturity, Fair Value	449,000,000		449,000,000
Non-US Debt Securities, Government Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	3,197,000,000		1,671,000,000
Available For Sale, Gross Unrealized Gains	2,000,000		0
Available for sale, Gross Unrealized Losses	0		0
Available for sale, Fair Value	3,199,000,000		1,671,000,000
Held to maturity, Amortized Cost	3,000,000		3,000,000
Held to maturity, Gross Unrealized Gains	0		0
Held to maturity, Gross Unrealized Losses	0		0
Held to maturity, Fair Value	3,000,000		3,000,000
Non-US Debt Securities, Other [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	4,221,000,000		2,797,000,000
Available For Sale, Gross Unrealized Gains	86,000,000		41,000,000
Available for sale, Gross Unrealized Losses	1,000,000		13,000,000
Available for sale, Fair Value	4,306,000,000		2,825,000,000
Held to maturity, Amortized Cost	167,000,000		172,000,000
Held to maturity, Gross Unrealized Gains	0		0
Held to maturity, Gross Unrealized Losses	2,000,000		17,000,000
Held to maturity, Fair Value	165,000,000		155,000,000
Non U S Debt Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	24,717,000,000		19,676,000,000
Available For Sale, Gross Unrealized Gains	443,000,000		135,000,000
Available for sale, Gross Unrealized Losses	32,000,000		137,000,000
Available for sale, Fair Value	25,128,000,000		19,674,000,000
Held to maturity, Amortized Cost	3,726,000,000		5,584,000,000
Held to maturity, Gross Unrealized Gains	101,000,000		103,000,000
Held to maturity, Gross Unrealized Losses	71,000,000		244,000,000
Held to maturity, Fair Value	3,756,000,000		5,443,000,000
State And Political Subdivisions [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	7,384,000,000		6,924,000,000
Available For Sale, Gross Unrealized Gains	234,000,000		244,000,000
Available for sale, Gross Unrealized Losses	67,000,000		121,000,000
Available for sale, Fair Value	7,551,000,000		7,047,000,000
Held to maturity, Amortized Cost	74,000,000		107,000,000
Held to maturity, Gross Unrealized Gains	2,000,000		3,000,000
Held to maturity, Gross Unrealized Losses	0		0
Held to maturity, Fair Value	76,000,000		110,000,000
Collateralized Mortgage Obligations [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	4,818,000,000		3,971,000,000
Available For Sale, Gross Unrealized Gains	151,000,000		62,000,000
Available for sale, Gross Unrealized Losses	15,000,000		53,000,000
Available for sale, Fair Value	4,954,000,000		3,980,000,000
Held to maturity, Amortized Cost	2,410,000,000		3,334,000,000
Held to maturity, Gross Unrealized Gains	259,000,000		220,000,000
Held to maturity, Gross Unrealized Losses	12,000,000		57,000,000
Held to maturity, Fair Value	2,657,000,000		3,497,000,000
Other U.S. Debt Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	5,072,000,000		3,471,000,000
Available For Sale, Gross Unrealized Gains	233,000,000		159,000,000
Available for sale, Gross Unrealized Losses	7,000,000		15,000,000
Available for sale, Fair Value	5,298,000,000		3,615,000,000
U.S. Equity Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	1,089,000,000		639,000,000
Available For Sale, Gross Unrealized Gains	3,000,000		1,000,000
Available for sale, Gross Unrealized Losses	0		0
Available for sale, Fair Value	1,092,000,000		640,000,000
Non-US Equity Securities [Member]
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available For Sale, Amortized Cost	123,000,000		118,000,000
Available For Sale, Gross Unrealized Gains	0		0
Available for sale, Gross Unrealized Losses	0		0
Available for sale, Fair Value	$ 123,000,000		$ 118,000,000

[1] Substantially composed of securities guaranteed by the federal government with respect to at least 97% of defaulted principal and accrued interest on the underlying loans.