Fair Value Disclosures (Schedule of Assets and Liabilities Measured at Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Trading securities	$ 485	$ 381
AFS securities	21,174	22,104
LHFS	2,001	1,222
Residential MSRs	943	1,047	956	627
Private equity and similar investments	305	291
Assets measured at fair value	25,724	25,909
Short-term borrowings	159	84
Total liabilities	919	1,054
Level 1 [Member]
Trading securities	279	256
LHFS	0	0
Residential MSRs	0	0
Private equity and similar investments	0	0
Assets measured at fair value	286	266
Short-term borrowings	0	0
Total liabilities	0	0
Level 2 [Member]
Trading securities	206	125
LHFS	2,001	1,222
Residential MSRs	0	0
Private equity and similar investments	0	0
Assets measured at fair value	23,403	23,441
Short-term borrowings	159	84
Total liabilities	917	1,040
Level 3 [Member]
Trading securities	0	0
LHFS	0	0
Residential MSRs	943	1,047
Private equity and similar investments	305	291
Assets measured at fair value	2,035	2,202
Short-term borrowings	0	0
Total liabilities	2	14
U.S. Treasury Securities
AFS securities	992	595
U.S. Treasury Securities | Level 2 [Member]
AFS securities	992	595
MBS Issued by GSE
AFS securities	16,613	17,929
MBS Issued by GSE | Level 2 [Member]
AFS securities	16,613	17,929
States and Political Subdivisions [Member]
AFS securities	1,965	1,851
States and Political Subdivisions [Member] | Level 2 [Member]
AFS securities	1,965	1,851
Non-Agency MBS [Member]
AFS securities	277	291
Non-Agency MBS [Member] | Level 2 [Member]
AFS securities	277	291
Other Securities [Member]
AFS securities	42	45
Other Securities [Member] | Level 1 [Member]
AFS securities	7	10
Other Securities [Member] | Level 2 [Member]
AFS securities	35	35
Covered Securities [Member]
AFS securities	1,285	1,393
Covered Securities [Member] | Level 2 [Member]
AFS securities	510	532
Covered Securities [Member] | Level 3 [Member]
AFS securities	775	861
Interest Rate Contract [Member]
Derivative assets	807	862
Derivative liabilities	755	967
Interest Rate Contract [Member] | Level 2 [Member]
Derivative assets	795	859
Derivative liabilities	753	953
Interest Rate Contract [Member] | Level 3 [Member]
Derivative assets	12	3
Derivative liabilities	2	14
Foreign Exchange Contracts [Member]
Derivative assets	9	2
Derivative liabilities	5	3
Foreign Exchange Contracts [Member] | Level 2 [Member]
Derivative assets	9	2
Derivative liabilities	$ 5	$ 3