Investment Securities (Schedule of Contractual Maturities of Debt Securities) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	$ 9,169
Available for sale, 1 to 5 Years	38,264
Available for sale, 6 to 10 Years	19,993
Available for sale, Over 10 Years	31,562
Held to maturity, Under 1 Year	327
Held to maturity, 1 to 5 Years	4,011
Held to maturity, 6 to 10 Years	6,022
Held to maturity, Over 10 Years	5,108
Total asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	3,859
Available for sale, 1 to 5 Years	13,176
Available for sale, 6 to 10 Years	8,095
Available for sale, Over 10 Years	4,863
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	705
Held to maturity, 6 to 10 Years	570
Held to maturity, Over 10 Years	976
US Treasury and federal agencies, direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	3
Available for sale, 1 to 5 Years	38
Available for sale, 6 to 10 Years	55
Available for sale, Over 10 Years	681
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	5,000
Held to maturity, Over 10 Years	0
US Treasury and federal agencies, mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	112
Available for sale, 1 to 5 Years	2,115
Available for sale, 6 to 10 Years	5,825
Available for sale, Over 10 Years	18,410
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	25
Held to maturity, 6 to 10 Years	26
Held to maturity, Over 10 Years	63
Asset-backed securities, student loans
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,120
Available for sale, 1 to 5 Years	6,709
Available for sale, 6 to 10 Years	4,493
Available for sale, Over 10 Years	2,818
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	154
Held to maturity, 6 to 10 Years	170
Held to maturity, Over 10 Years	970
Asset-backed securities, credit cards
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	2,574
Available for sale, 1 to 5 Years	4,366
Available for sale, 6 to 10 Years	2,194
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	10
Held to maturity, 6 to 10 Years	58
Held to maturity, Over 10 Years	0
Asset-backed securities, sub-prime
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	25
Available for sale, 1 to 5 Years	30
Available for sale, 6 to 10 Years	2
Available for sale, Over 10 Years	1,268
Asset-backed securities, other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	140
Available for sale, 1 to 5 Years	2,071
Available for sale, 6 to 10 Years	1,406
Available for sale, Over 10 Years	777
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	541
Held to maturity, 6 to 10 Years	342
Held to maturity, Over 10 Years	6
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	4,152
Available for sale, 1 to 5 Years	13,680
Available for sale, 6 to 10 Years	1,062
Available for sale, Over 10 Years	4,702
Held to maturity, Under 1 Year	137
Held to maturity, 1 to 5 Years	2,057
Held to maturity, 6 to 10 Years	47
Held to maturity, Over 10 Years	2,934
Non-U.S. debt securities, mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	226
Available for sale, 1 to 5 Years	5,458
Available for sale, 6 to 10 Years	183
Available for sale, Over 10 Years	4,524
Held to maturity, Under 1 Year	57
Held to maturity, 1 to 5 Years	823
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	2,929
Non-U.S. debt securities, asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	306
Available for sale, 1 to 5 Years	4,657
Available for sale, 6 to 10 Years	326
Available for sale, Over 10 Years	178
Held to maturity, Under 1 Year	65
Held to maturity, 1 to 5 Years	1,055
Held to maturity, 6 to 10 Years	47
Held to maturity, Over 10 Years	0
Non-US debt securities, government securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	2,445
Available for sale, 1 to 5 Years	985
Available for sale, 6 to 10 Years	0
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	15
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	0
Non-U.S. debt securities, other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,175
Available for sale, 1 to 5 Years	2,580
Available for sale, 6 to 10 Years	553
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	179
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	5
State and political subdivisions
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	669
Available for sale, 1 to 5 Years	2,938
Available for sale, 6 to 10 Years	3,048
Available for sale, Over 10 Years	1,464
Held to maturity, Under 1 Year	50
Held to maturity, 1 to 5 Years	16
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	0
Collateralized mortgage obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	149
Available for sale, 1 to 5 Years	2,257
Available for sale, 6 to 10 Years	1,161
Available for sale, Over 10 Years	1,409
Held to maturity, Under 1 Year	140
Held to maturity, 1 to 5 Years	1,208
Held to maturity, 6 to 10 Years	379
Held to maturity, Over 10 Years	1,135
Other U.S.debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	225
Available for sale, 1 to 5 Years	4,060
Available for sale, 6 to 10 Years	747
Available for sale, Over 10 Years	$ 33