Deposits (Summary of Deposits) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Deposits By Type [Line Items]
Noninterest-bearing deposits	$ 30,810	$ 25,684
Interest-bearing deposits	99,208	99,255
Total deposits	130,018	124,939
Time deposits $100,000 and greater	18,291	19,819
Interest Checking [Member]
Deposits By Type [Line Items]
Interest-bearing deposits	20,182	20,701
Money Market And Savings [Member]
Deposits By Type [Line Items]
Interest-bearing deposits	48,099	44,618
Certificates And Other Time Deposits [Member]
Deposits By Type [Line Items]
Interest-bearing deposits	30,927	33,899
Foreign Office Deposits - Interest-Bearing [Member]
Deposits By Type [Line Items]
Interest-bearing deposits	$ 0	$ 37