Fair Value Disclosures (Schedule of Assets and Liabilities Measured at Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Trading securities	$ 1,180	$ 482
AFS securities	25,297	20,907
LHFS	1,035	1,423
Residential MSRs	880	844	$ 1,047	$ 627
Derivative assets	970	1,122
Private equity and similar investments	289	329
Assets measured at fair value	29,651	25,107
Derivative liabilities	792	1,013
Securities sold short	147	148
Total liabilities	939	1,161
Level 1 [Member]
Trading securities	311	289
LHFS	0	0
Residential MSRs	0	0
Private equity and similar investments	0	0
Assets measured at fair value	315	295
Securities sold short	0	0
Total liabilities	0	0
Level 2 [Member]
Trading securities	869	193
LHFS	1,035	1,423
Residential MSRs	0	0
Private equity and similar investments	0	0
Assets measured at fair value	27,533	22,874
Securities sold short	147	148
Total liabilities	935	1,158
Level 3 [Member]
Trading securities	0	0
LHFS	0	0
Residential MSRs	880	844
Private equity and similar investments	289	329
Assets measured at fair value	1,803	1,938
Securities sold short	0	0
Total liabilities	4	3
U.S. Treasury Securities
AFS securities	1,832	1,231
U.S. Treasury Securities | Level 2 [Member]
AFS securities	1,832	1,231
GSE Securities
AFS securities	51
GSE Securities | Level 2 [Member]
AFS securities	51
Agency MBS [Member]
AFS securities	20,046	16,154
Agency MBS [Member] | Level 2 [Member]
AFS securities	20,046	16,154
States and Political Subdivisions [Member]
AFS securities	2,079	1,974
States and Political Subdivisions [Member] | Level 2 [Member]
AFS securities	2,079	1,974
Non-Agency MBS [Member]
AFS securities	221	264
Non-Agency MBS [Member] | Level 2 [Member]
AFS securities	221	264
Other Securities [Member]
AFS securities	4	41
Other Securities [Member] | Level 1 [Member]
AFS securities	4	6
Other Securities [Member] | Level 2 [Member]
AFS securities	0	35
Acquired from FDIC Securities [Member]
AFS securities	1,064	1,243
Acquired from FDIC Securities [Member] | Level 2 [Member]
AFS securities	438	498
Acquired from FDIC Securities [Member] | Level 3 [Member]
AFS securities	626	745
Interest Rate Contracts [Member]
Derivative assets	964	1,114
Derivative liabilities	788	1,007
Interest Rate Contracts [Member] | Level 2 [Member]
Derivative assets	956	1,094
Derivative liabilities	784	1,004
Interest Rate Contracts [Member] | Level 3 [Member]
Derivative assets	8	20
Derivative liabilities	4	3
Foreign Exchange Contracts [Member]
Derivative assets	6	8
Derivative liabilities	4	6
Foreign Exchange Contracts [Member] | Level 2 [Member]
Derivative assets	6	8
Derivative liabilities	$ 4	$ 6