Investment Securities (Schedule Of Contractual Maturities Of Debt Securities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	$ 6,761
Available for sale, 1 to 5 Years	40,481
Available for sale, 6 to 10 Years	24,098
Available for sale, Over 10 Years	37,127
Held to maturity, Under 1 Year	529
Held to maturity, 1 to 5 Years	1,716
Held to maturity, 6 to 10 Years	4,750
Held to maturity, Over 10 Years	4,384
US Treasury and Federal Agencies, Direct Obligations [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	4
Available for sale, 1 to 5 Years	43
Available for sale, 6 to 10 Years	61
Available for sale, Over 10 Years	733
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	4,500
Held to maturity, Over 10 Years	500
US Treasury and Federal Agencies, Mortgage-backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	10
Available for sale, 1 to 5 Years	2,458
Available for sale, 6 to 10 Years	7,139
Available for sale, Over 10 Years	22,605
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	36
Held to maturity, 6 to 10 Years	32
Held to maturity, Over 10 Years	85
Asset-backed Securities, Student Loans [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	425
Available for sale, 1 to 5 Years	6,863
Available for sale, 6 to 10 Years	5,540
Available for sale, Over 10 Years	3,593
Asset-backed Securities, Credit Cards [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,102
Available for sale, 1 to 5 Years	5,967
Available for sale, 6 to 10 Years	2,917
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	56
Available for sale, 1 to 5 Years	51
Available for sale, 6 to 10 Years	4
Available for sale, Over 10 Years	1,288
Asset-backed Securities, Other [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	178
Available for sale, 1 to 5 Years	2,199
Available for sale, 6 to 10 Years	1,588
Available for sale, Over 10 Years	712
Asset-backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,761
Available for sale, 1 to 5 Years	15,080
Available for sale, 6 to 10 Years	10,049
Available for sale, Over 10 Years	5,593
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	9
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	7
Non-US Debt Securities, Mortgage-Backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	160
Available for sale, 1 to 5 Years	5,484
Available for sale, 6 to 10 Years	73
Available for sale, Over 10 Years	5,688
Held to maturity, Under 1 Year	93
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	3,029
Non-US Debt Securities, Asset-Backed Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	272
Available for sale, 1 to 5 Years	4,579
Available for sale, 6 to 10 Years	1,063
Available for sale, Over 10 Years	304
Held to maturity, Under 1 Year	149
Held to maturity, 1 to 5 Years	238
Held to maturity, 6 to 10 Years	47
Held to maturity, Over 10 Years	0
Non-US Debt Securities, Government Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	2,064
Available for sale, 1 to 5 Years	1,135
Available for sale, 6 to 10 Years	0
Available for sale, Over 10 Years	0
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]
Available for sale, Under 1 Year	1,373
Available for sale, 1 to 5 Years	2,534
Available for sale, 6 to 10 Years	399
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	158
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	9
Non-US Equity Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	3,869
Available for sale, 1 to 5 Years	13,732
Available for sale, 6 to 10 Years	1,535
Available for sale, Over 10 Years	5,992
Non U S Debt Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, Under 1 Year	245
Held to maturity, 1 to 5 Years	396
Held to maturity, 6 to 10 Years	47
Held to maturity, Over 10 Years	3,038
State And Political Subdivisions [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	685
Available for sale, 1 to 5 Years	3,075
Available for sale, 6 to 10 Years	2,882
Available for sale, Over 10 Years	909
Held to maturity, Under 1 Year	49
Held to maturity, 1 to 5 Years	25
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]
Available for sale, Under 1 Year	161
Available for sale, 1 to 5 Years	2,371
Available for sale, 6 to 10 Years	1,161
Available for sale, Over 10 Years	1,261
Held to maturity, Under 1 Year	235
Held to maturity, 1 to 5 Years	1,250
Held to maturity, 6 to 10 Years	171
Held to maturity, Over 10 Years	754
Other U.S. Debt Securities [Member]
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	271
Available for sale, 1 to 5 Years	3,722
Available for sale, 6 to 10 Years	1,271
Available for sale, Over 10 Years	$ 34