Securities - U.S. GSE, Agency, and Treasury Securities (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 330,440	$ 353,268
Fair Value	321,225	361,120
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	123,813	121,522
Fair Value	118,708	123,933
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	118,700	124,348
Fair Value	115,314	127,541
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	24,908	22,995
Fair Value	$ 24,075	$ 23,502