Deposits (Schedule of Interest Bearing Deposit Accounts) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Deposits [Abstract]    
Certificates of deposit in amounts less than $100,000 $ 21,235 [1] $ 21,502 [1]
Certificates of deposit from amounts of $100,000 to less than $250,000 4,397 [1] 4,481 [1]
Certificates of deposit in amounts of $250,000 or greater 1,146 [1] 1,153 [1]
Savings deposits, including money market deposit accounts 19,346 18,656
Total interest-bearing deposits $ 46,124 $ 45,792
Average annual interest rate (in percent) 1.27% 1.29%
[1] $100,000 represents the basic insurance amount previously covered by the Federal Deposit Insurance Corporation (the "FDIC"). Effective July 21, 2010, the basic insurance per depositor was permanently increased to $250,000.