v3.4.0.3
Investment Securities (Schedule of Investment Securities) (Details) - USD ($)
$ in Millions
Mar. 31, 2016
Dec. 31, 2015
Investment securities    
Total Investment securities, Amortized cost $ 77,477 $ 72,493
Total Investment securities, Gross unrealized gains 408 44
Total Investment securities, Gross unrealized losses 240 590
Total Investment securities, fair value 77,645 71,947
AFS securities    
Total AFS securities, fair value $ 68,167 $ 66,759
FFELP Student Loan Asset-backed Securities    
Investment securities    
Percent of principal balance and interest guaranteed by the U.S. Department of Education 95.00% 95.00%
AFS securities    
AFS securities    
AFS debt securities, Amortized cost $ 68,052 $ 67,269
Total AFS securities, Gross unrealized gains 354 43
Total AFS securities, Gross unrealized loss 239 553
Total AFS securities, fair value 68,167 66,759
AFS Debt Securities    
AFS securities    
AFS debt securities, Amortized cost 68,037 67,254
AFS debt securities, Gross unrealized gains 354 43
AFS debt securities, Gross unrealized losses 233 545
AFS debt securities, Fair value 68,158 66,752
AFS Debt Securities | U.S. Government and Agency Securities    
AFS securities    
AFS debt securities, Amortized cost 53,470 52,658
AFS debt securities, Gross unrealized gains 278 34
AFS debt securities, Gross unrealized losses 36 299
AFS debt securities, Fair value 53,712 52,393
AFS Debt Securities | U.S. Treasury Securities    
AFS securities    
AFS debt securities, Amortized cost 31,808 31,555
AFS debt securities, Gross unrealized gains 151 5
AFS debt securities, Gross unrealized losses 1 143
AFS debt securities, Fair value 31,958 31,417
AFS Debt Securities | U.S. Agency Securities    
AFS securities    
AFS debt securities, Amortized cost 21,662 21,103
AFS debt securities, Gross unrealized gains 127 29
AFS debt securities, Gross unrealized losses 35 156
AFS debt securities, Fair value 21,754 20,976
AFS Debt Securities | Corporate and Other Debt    
AFS securities    
AFS debt securities, Amortized cost 14,567 14,596
AFS debt securities, Gross unrealized gains 76 9
AFS debt securities, Gross unrealized losses 197 246
AFS debt securities, Fair value 14,446 14,359
AFS Debt Securities | Agency    
AFS securities    
AFS debt securities, Amortized cost 2,154 1,906
AFS debt securities, Gross unrealized gains 4 1
AFS debt securities, Gross unrealized losses 38 60
AFS debt securities, Fair value 2,120 1,847
AFS Debt Securities | Non-Agency    
AFS securities    
AFS debt securities, Amortized cost 2,164 2,220
AFS debt securities, Gross unrealized gains 23 3
AFS debt securities, Gross unrealized losses 14 25
AFS debt securities, Fair value 2,173 2,198
AFS Debt Securities | Auto Loan Asset-backed Securities    
AFS securities    
AFS debt securities, Amortized cost 2,328 2,556
AFS debt securities, Gross unrealized gains 2 0
AFS debt securities, Gross unrealized losses 1 9
AFS debt securities, Fair value 2,329 2,547
AFS Debt Securities | Corporate Bonds    
AFS securities    
AFS debt securities, Amortized cost 3,930 3,780
AFS debt securities, Gross unrealized gains 47 5
AFS debt securities, Gross unrealized losses 7 30
AFS debt securities, Fair value 3,970 3,755
AFS Debt Securities | Collateralized Loan Obligations    
AFS securities    
AFS debt securities, Amortized cost 502 502
AFS debt securities, Gross unrealized gains 0 0
AFS debt securities, Gross unrealized losses 10 7
AFS debt securities, Fair value 492 495
AFS Debt Securities | FFELP Student Loan Asset-backed Securities    
AFS securities    
AFS debt securities, Amortized cost 3,489 3,632
AFS debt securities, Gross unrealized gains 0 0
AFS debt securities, Gross unrealized losses 127 115
AFS debt securities, Fair value 3,362 3,517
AFS Equity Securities    
AFS securities    
AFS equity securities, Amortized cost 15 15
AFS equity securities, Gross unrealized gains 0 0
AFS equity securities, Gross unrealized losses 6 8
AFS equity securities, Fair value 9 7
HTM securities    
HTM securities:    
HTM - Amortized Cost 9,425 5,224
HTM - Gross Unrealized Gains 54 1
HTM - Gross Unrealized Losses 1 37
HTM - Fair Value 9,478 5,188
HTM securities | U.S. Treasury Securities    
HTM securities:    
HTM - Amortized Cost 1,953 1,001
HTM - Gross Unrealized Gains 10 0
HTM - Gross Unrealized Losses 0 3
HTM - Fair Value 1,963 998
HTM securities | U.S. Agency Securities    
HTM securities:    
HTM - Amortized Cost 7,472 4,223
HTM - Gross Unrealized Gains 44 1
HTM - Gross Unrealized Losses 1 34
HTM - Fair Value $ 7,515 $ 4,190