Investment Securities (Schedule Of Contractual Maturities Of Debt Securities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	$ 6,279
Available for sale, 1 to 5 Years	38,116
Available for sale, 6 to 10 Years	26,346
Available for sale, Over 10 Years	35,377
Held to maturity, Under 1 Year	766
Held to maturity, 1 to 5 Years	1,821
Held to maturity, 6 to 10 Years	201
Held to maturity, Over 10 Years	5,572
US Treasury and Federal Agencies, Mortgage-backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, 1 to 5 Years	43
Held to maturity, 6 to 10 Years	36
Held to maturity, Over 10 Years	101
Asset-backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	8
Non-US Debt Securities, Mortgage-Backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, Under 1 Year	256
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	3,153
Non-US Debt Securities, Asset-Backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, Under 1 Year	75
Held to maturity, 1 to 5 Years	320
Held to maturity, 6 to 10 Years	46
Held to maturity, Over 10 Years	0
Non-US Debt Securities, Government Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, Under 1 Year	3
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	0
Non-US Debt Securities, Other [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	154
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	11
Non U S Debt Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, Under 1 Year	334
Held to maturity, 1 to 5 Years	474
Held to maturity, 6 to 10 Years	46
Held to maturity, Over 10 Years	3,164
State And Political Subdivisions [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, Under 1 Year	50
Held to maturity, 1 to 5 Years	30
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	0
Collateralized Mortgage Obligations [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, Under 1 Year	382
Held to maturity, 1 to 5 Years	1,274
Held to maturity, 6 to 10 Years	119
Held to maturity, Over 10 Years	799
US Treasury and Federal Agencies, Direct Obligations [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, 1 to 5 Years	52
Available for sale, 6 to 10 Years	60
Available for sale, Over 10 Years	758
Held to maturity, Over 10 Years	1,500
US Treasury and Federal Agencies, Mortgage-backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	13
Available for sale, 1 to 5 Years	1,447
Available for sale, 6 to 10 Years	8,858
Available for sale, Over 10 Years	21,685
Asset-backed Securities, Student Loans [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	316
Available for sale, 1 to 5 Years	6,573
Available for sale, 6 to 10 Years	6,261
Available for sale, Over 10 Years	3,387
Asset-backed Securities, Credit Cards [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	986
Available for sale, 1 to 5 Years	6,432
Available for sale, 6 to 10 Years	2,548
Available for sale, Over 10 Years	0
Asset-backed Securities, Sub-prime [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	109
Available for sale, 1 to 5 Years	52
Available for sale, 6 to 10 Years	4
Available for sale, Over 10 Years	1,214
Asset-backed Securities, Other [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	76
Available for sale, 1 to 5 Years	2,268
Available for sale, 6 to 10 Years	1,479
Available for sale, Over 10 Years	303
Asset-backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,487
Available for sale, 1 to 5 Years	15,325
Available for sale, 6 to 10 Years	10,292
Available for sale, Over 10 Years	4,904
Non-US Debt Securities, Mortgage-Backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	159
Available for sale, 1 to 5 Years	4,602
Available for sale, 6 to 10 Years	523
Available for sale, Over 10 Years	5,760
Non-US Debt Securities, Asset-Backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	313
Available for sale, 1 to 5 Years	4,198
Available for sale, 6 to 10 Years	1,131
Available for sale, Over 10 Years	278
Non-US Debt Securities, Government Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,726
Available for sale, 1 to 5 Years	1,260
Available for sale, 6 to 10 Years	0
Available for sale, Over 10 Years	0
Non-US Debt Securities, Other [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,475
Available for sale, 1 to 5 Years	2,178
Available for sale, 6 to 10 Years	381
Available for sale, Over 10 Years	0
Non-US Equity Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	3,673
Available for sale, 1 to 5 Years	12,238
Available for sale, 6 to 10 Years	2,035
Available for sale, Over 10 Years	6,038
State And Political Subdivisions [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	640
Available for sale, 1 to 5 Years	3,086
Available for sale, 6 to 10 Years	2,835
Available for sale, Over 10 Years	743
Collateralized Mortgage Obligations [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	151
Available for sale, 1 to 5 Years	2,412
Available for sale, 6 to 10 Years	1,064
Available for sale, Over 10 Years	1,218
Other U.S. Debt Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	315
Available for sale, 1 to 5 Years	3,556
Available for sale, 6 to 10 Years	1,202
Available for sale, Over 10 Years	$ 31