Deposits (Summary of Deposits) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Deposits By Type [Line Items]
Noninterest-bearing deposits	$ 27,410	$ 25,684
Interest-bearing deposits	96,747	99,255
Total deposits	124,157	124,939
Interest Checking [Member]
Deposits By Type [Line Items]
Interest-bearing deposits	20,318	20,701
Money Market And Savings [Member]
Deposits By Type [Line Items]
Interest-bearing deposits	46,759	44,618
Certificates And Other Time Deposits [Member]
Deposits By Type [Line Items]
Interest-bearing deposits	29,648	33,899
Foreign Office Deposits - Interest-Bearing [Member]
Deposits By Type [Line Items]
Interest-bearing deposits	$ 22	$ 37