Investment Securities (Schedule of Contractual Maturities of Debt Securities) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	$ 11,103
Available for sale, 1 to 5 Years	34,694
Available for sale, 6 to 10 Years	22,432
Available for sale, Over 10 Years	29,657
Held to maturity, Under 1 Year	793
Held to maturity, 1 to 5 Years	5,589
Held to maturity, 6 to 10 Years	7,251
Held to maturity, Over 10 Years	5,124
Total asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	2,541
Available for sale, 1 to 5 Years	11,222
Available for sale, 6 to 10 Years	7,062
Available for sale, Over 10 Years	5,439
Held to maturity, Under 1 Year	33
Held to maturity, 1 to 5 Years	958
Held to maturity, 6 to 10 Years	1,169
Held to maturity, Over 10 Years	1,329
US Treasury and federal agencies, direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	2
Available for sale, 1 to 5 Years	783
Available for sale, 6 to 10 Years	2,079
Available for sale, Over 10 Years	571
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	119
US Treasury and federal agencies, mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	197
Available for sale, 1 to 5 Years	2,295
Available for sale, 6 to 10 Years	5,141
Available for sale, Over 10 Years	14,506
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	18
Held to maturity, 6 to 10 Years	13
Held to maturity, Over 10 Years	43
Asset-backed securities, student loans
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	378
Available for sale, 1 to 5 Years	6,718
Available for sale, 6 to 10 Years	4,219
Available for sale, Over 10 Years	2,647
Held to maturity, Under 1 Year	9
Held to maturity, 1 to 5 Years	182
Held to maturity, 6 to 10 Years	385
Held to maturity, Over 10 Years	1,324
Asset-backed securities, credit cards
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,650
Available for sale, 1 to 5 Years	3,261
Available for sale, 6 to 10 Years	1,655
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	335
Held to maturity, 6 to 10 Years	562
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	7
Available for sale, 1 to 5 Years	19
Available for sale, 6 to 10 Years	1
Available for sale, Over 10 Years	1,074
Asset-backed securities, other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	506
Available for sale, 1 to 5 Years	1,224
Available for sale, 6 to 10 Years	1,187
Available for sale, Over 10 Years	1,718
Held to maturity, Under 1 Year	24
Held to maturity, 1 to 5 Years	441
Held to maturity, 6 to 10 Years	222
Held to maturity, Over 10 Years	5
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	6,659
Available for sale, 1 to 5 Years	12,474
Available for sale, 6 to 10 Years	2,031
Available for sale, Over 10 Years	4,051
Held to maturity, Under 1 Year	261
Held to maturity, 1 to 5 Years	3,913
Held to maturity, 6 to 10 Years	559
Held to maturity, Over 10 Years	2,686
Non-U.S. debt securities, mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	2,055
Available for sale, 1 to 5 Years	5,053
Available for sale, 6 to 10 Years	403
Available for sale, Over 10 Years	3,924
Held to maturity, Under 1 Year	87
Held to maturity, 1 to 5 Years	1,320
Held to maturity, 6 to 10 Years	181
Held to maturity, Over 10 Years	2,686
Non-U.S. debt securities, asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	333
Available for sale, 1 to 5 Years	3,176
Available for sale, 6 to 10 Years	564
Available for sale, Over 10 Years	127
Held to maturity, Under 1 Year	7
Held to maturity, 1 to 5 Years	2,513
Held to maturity, 6 to 10 Years	378
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	2,233
Available for sale, 1 to 5 Years	1,590
Available for sale, 6 to 10 Years	0
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	2
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	2,038
Available for sale, 1 to 5 Years	2,655
Available for sale, 6 to 10 Years	1,064
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	165
Held to maturity, 1 to 5 Years	80
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	0
State and political subdivisions
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	670
Available for sale, 1 to 5 Years	3,032
Available for sale, 6 to 10 Years	4,321
Available for sale, Over 10 Years	2,594
Held to maturity, Under 1 Year	12
Held to maturity, 1 to 5 Years	3
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	397
Available for sale, 1 to 5 Years	1,403
Available for sale, 6 to 10 Years	1,113
Available for sale, Over 10 Years	2,461
Held to maturity, Under 1 Year	487
Held to maturity, 1 to 5 Years	697
Held to maturity, 6 to 10 Years	510
Held to maturity, Over 10 Years	947
Other U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	637
Available for sale, 1 to 5 Years	3,485
Available for sale, 6 to 10 Years	685
Available for sale, Over 10 Years	$ 35