v2.4.0.6
Securities Available for Sale (Schedule of Amortized Cost and Fair Value of Available for Sale Debt Securities by Contractual Date) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Amortized Cost, Total $ 39,597
Fair Value, Total 39,861
Annualized Average Yield, Total 0.90%
U.S. Government and Agency Securities
  
Amortized Cost, Total 29,681
Fair Value, Total 29,907
Annualized Average Yield, Total 0.90%
U.S. Treasury Securities
  
Amortized Cost, Due within 1 year 753
Fair Value, Due within 1 year 757
Annualized Average Yield, Due within 1 year 0.80%
Amortized Cost, After 1 year but through 5 years 13,492
Fair Value, After 1 year but through 5 years 13,592
Annualized Average Yield, After 1 year but through 5 years 0.70%
Amortized Cost, After 5 years 106
Fair value, After 5 years 109
Annualized Average Yield, After 5 years 1.50%
Amortized Cost, Total 14,351
Fair Value, Total 14,458
U.S. Agency Securities
  
Amortized Cost, After 1 year but through 5 years 0
Fair Value, After 1 year but through 5 years 0
Annualized Average Yield, After 1 year but through 5 years 0.00%
Amortized Cost, After 5 years 15,330
Fair value, After 5 years 15,449
Annualized Average Yield, After 5 years 1.00%
Amortized Cost, Total 15,330
Fair Value, Total 15,449
Corporate and Other Debt
  
Amortized Cost, Total 9,916
Fair Value, Total 9,954
Annualized Average Yield, Total 1.00%
Agency
  
Amortized Cost, After 1 year but through 5 years 353
Fair Value, After 1 year but through 5 years 354
Annualized Average Yield, After 1 year but through 5 years 1.00%
Amortized Cost, After 5 years 1,844
Fair value, After 5 years 1,845
Annualized Average Yield, After 5 years 1.30%
Amortized Cost, Total 2,197
Fair Value, Total 2,199
Non-Agency
  
Amortized Cost, After 5 years 160
Fair value, After 5 years 160
Annualized Average Yield, After 5 years 0.70%
Amortized Cost, Total 160
Fair Value, Total 160
Auto Loan Asset-backed Securities
  
Amortized Cost, After 1 year but through 5 years 1,642
Fair Value, After 1 year but through 5 years 1,645
Annualized Average Yield, After 1 year but through 5 years 0.70%
Amortized Cost, After 5 years 351
Fair value, After 5 years 351
Annualized Average Yield, After 5 years 0.70%
Amortized Cost, Total 1,993
Fair Value, Total 1,996
Corporate Bonds
  
Amortized Cost, Due within 1 year 153
Fair Value, Due within 1 year 153
Annualized Average Yield, Due within 1 year 0.70%
Amortized Cost, After 1 year but through 5 years 2,589
Fair Value, After 1 year but through 5 years 2,599
Annualized Average Yield, After 1 year but through 5 years 1.10%
Amortized Cost, After 5 years 149
Fair value, After 5 years 149
Annualized Average Yield, After 5 years 1.20%
Amortized Cost, Total 2,891
Fair Value, Total 2,901
FFELP Student Loan Asset-backed Securities
  
Amortized Cost, After 1 year but through 5 years 94
Fair Value, After 1 year but through 5 years 95
Annualized Average Yield, After 1 year but through 5 years 0.90%
Amortized Cost, After 5 years 2,581
Fair value, After 5 years 2,603
Annualized Average Yield, After 5 years 1.10%
Amortized Cost, Total 2,675
Fair Value, Total $ 2,698