Investment Securities (Schedule of Marketable Securities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 99,159		$ 108,563
Available for sale, gross unrealized gains	1,162		2,001
Available for sale, gross unrealized losses	1,147		882
Available for sale, fair value	99,174		109,682
Held to maturity, amortized cost	17,740		11,379
Held to maturity, gross unrealized gains	354		373
Held to maturity, gross unrealized losses	534		91
Held to maturity, fair value	17,560		11,661
Total asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	29,188		32,897
Available for sale, gross unrealized gains	254		320
Available for sale, gross unrealized losses	423		734
Available for sale, fair value	29,019		32,483
Held to maturity, amortized cost	3,171		16
Held to maturity, gross unrealized gains	2		0
Held to maturity, gross unrealized losses	12		0
Held to maturity, fair value	3,161		16
US Treasury and federal agencies, direct obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	702		823
Available for sale, gross unrealized gains	9		19
Available for sale, gross unrealized losses	2		1
Available for sale, fair value	709		841
Held to maturity, amortized cost	5,041		5,000
Held to maturity, gross unrealized gains	0		0
Held to maturity, gross unrealized losses	448		8
Held to maturity, fair value	4,593		4,992
US Treasury and federal agencies, mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	23,744		31,640
Available for sale, gross unrealized gains	211		598
Available for sale, gross unrealized losses	392		26
Available for sale, fair value	23,563		32,212
Held to maturity, amortized cost	91		153
Held to maturity, gross unrealized gains	6		11
Held to maturity, gross unrealized losses	0		0
Held to maturity, fair value	97		164
Asset-backed securities, student loans
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	14,718	[1]	16,829	[1]
Available for sale, gross unrealized gains	92	[1]	100	[1]
Available for sale, gross unrealized losses	268	[1]	508	[1]
Available for sale, fair value	14,542	[1]	16,421	[1]
Held to maturity, amortized cost	1,627	[1]	0	[1]
Held to maturity, gross unrealized gains	0	[1]	0	[1]
Held to maturity, gross unrealized losses	10	[1]	0	[1]
Held to maturity, fair value	1,617	[1]	0	[1]
Asset-backed securities, credit cards
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	8,230		9,928
Available for sale, gross unrealized gains	21		61
Available for sale, gross unrealized losses	41		3
Available for sale, fair value	8,210		9,986
Held to maturity, amortized cost	762		0
Held to maturity, gross unrealized gains	1		0
Held to maturity, gross unrealized losses	0		0
Held to maturity, fair value	763		0
Asset-backed securities, sub-prime
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	1,291		1,557
Available for sale, gross unrealized gains	3		4
Available for sale, gross unrealized losses	91		162
Available for sale, fair value	1,203		1,399
Asset-backed securities, other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	4,949		4,583
Available for sale, gross unrealized gains	138		155
Available for sale, gross unrealized losses	23		61
Available for sale, fair value	5,064		4,677
Held to maturity, amortized cost	782		16
Held to maturity, gross unrealized gains	1		0
Held to maturity, gross unrealized losses	2		0
Held to maturity, fair value	781		16
Total non-U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	24,615		24,717
Available for sale, gross unrealized gains	314		443
Available for sale, gross unrealized losses	22		32
Available for sale, fair value	24,907		25,128
Held to maturity, amortized cost	6,607		3,726
Held to maturity, gross unrealized gains	169		101
Held to maturity, gross unrealized losses	48		71
Held to maturity, fair value	6,728		3,756
Non-U.S. debt securities, mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	10,808		11,119
Available for sale, gross unrealized gains	230		313
Available for sale, gross unrealized losses	9		27
Available for sale, fair value	11,029		11,405
Held to maturity, amortized cost	4,211		3,122
Held to maturity, gross unrealized gains	150		85
Held to maturity, gross unrealized losses	48		68
Held to maturity, fair value	4,313		3,139
Non-U.S. debt securities, asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	5,369		6,180
Available for sale, gross unrealized gains	23		42
Available for sale, gross unrealized losses	2		4
Available for sale, fair value	5,390		6,218
Held to maturity, amortized cost	2,202		434
Held to maturity, gross unrealized gains	19		16
Held to maturity, gross unrealized losses	0		1
Held to maturity, fair value	2,221		449
Non-US debt securities, government securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,759		3,197
Available for sale, gross unrealized gains	2		2
Available for sale, gross unrealized losses	0		0
Available for sale, fair value	3,761		3,199
Held to maturity, amortized cost	2		3
Held to maturity, gross unrealized gains	0		0
Held to maturity, gross unrealized losses	0		0
Held to maturity, fair value	2		3
Non-U.S. debt securities, other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	4,679		4,221
Available for sale, gross unrealized gains	59		86
Available for sale, gross unrealized losses	11		1
Available for sale, fair value	4,727		4,306
Held to maturity, amortized cost	192		167
Held to maturity, gross unrealized gains	0		0
Held to maturity, gross unrealized losses	0		2
Held to maturity, fair value	192		165
State and political subdivisions
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	10,301		7,384
Available for sale, gross unrealized gains	160		234
Available for sale, gross unrealized losses	198		67
Available for sale, fair value	10,263		7,551
Held to maturity, amortized cost	24		74
Held to maturity, gross unrealized gains	1		2
Held to maturity, gross unrealized losses	0		0
Held to maturity, fair value	25		76
Collateralized mortgage obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	5,275		4,818
Available for sale, gross unrealized gains	70		151
Available for sale, gross unrealized losses	76		15
Available for sale, fair value	5,269		4,954
Held to maturity, amortized cost	2,806		2,410
Held to maturity, gross unrealized gains	176		259
Held to maturity, gross unrealized losses	26		12
Held to maturity, fair value	2,956		2,657
Other U.S.debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	4,876		5,072
Available for sale, gross unrealized gains	138		233
Available for sale, gross unrealized losses	34		7
Available for sale, fair value	4,980		5,298
U.S. equity securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	28		28
Available for sale, gross unrealized gains	6		3
Available for sale, gross unrealized losses	0		0
Available for sale, fair value	34		31
Non-U.S. equity securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	1		1
Available for sale, gross unrealized gains	0		0
Available for sale, gross unrealized losses	0		0
Available for sale, fair value	1		1
U.S. money-market mutual funds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	422		1,062
Available for sale, gross unrealized gains	0		0
Available for sale, gross unrealized losses	0		0
Available for sale, fair value	422		1,062
Non-U.S. money-market mutual funds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	7		121
Available for sale, gross unrealized gains	0		0
Available for sale, gross unrealized losses	0		0
Available for sale, fair value	$ 7		$ 121

[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.