Fair Value Disclosures (Schedule of Assets and Liabilities Measured at Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Trading securities	$ 521	$ 497
AFS securities	22,865	25,137
LHFS, at fair value	2,957	3,761
Residential MSRs at fair value	956	627	563	563
Private equity and similar investments	288	323
Assets measured at fair value	28,583	31,795
Short-term borrowed funds	270	98
Total liabilities	1,426	1,535
Level 1 [Member]
Trading securities	237	302
LHFS, at fair value	0	0
Residential MSRs at fair value	0	0
Private equity and similar investments	0	0
Assets measured at fair value	253	304
Short-term borrowed funds	0	0
Total liabilities	0	0
Level 2 [Member]
Trading securities	265	194
LHFS, at fair value	2,957	3,761
Residential MSRs at fair value	0	0
Private equity and similar investments	0	0
Assets measured at fair value	26,118	29,491
Short-term borrowed funds	270	98
Total liabilities	1,425	1,534
Level 3 [Member]
Trading securities	19	1
LHFS, at fair value	0	0
Residential MSRs at fair value	956	627
Private equity and similar investments	288	323
Assets measured at fair value	2,212	2,000
Short-term borrowed funds	0	0
Total liabilities	1	1
GSE Securities
AFS securities	549	290
GSE Securities | Level 2 [Member]
AFS securities	549	290
MBS Issued by GSE
AFS securities	18,716	20,930
MBS Issued by GSE | Level 2 [Member]
AFS securities	18,716	20,930
States and Political Subdivisions [Member]
AFS securities	1,859	2,011
States and Political Subdivisions [Member] | Level 2 [Member]
AFS securities	1,859	2,011
Non-Agency MBS [Member]
AFS securities	278	312
Non-Agency MBS [Member] | Level 2 [Member]
AFS securities	278	312
Other Securities [Member]
AFS securities	17	3
Other Securities [Member] | Level 1 [Member]
AFS securities	16	2
Other Securities [Member] | Level 2 [Member]
AFS securities	1	1
Covered Securities [Member]
AFS securities	1,446	1,591
Covered Securities [Member] | Level 2 [Member]
AFS securities	544	597
Covered Securities [Member] | Level 3 [Member]
AFS securities	902	994
Interest Rate Contract [Member]
Derivative assets	994	1,446
Derivative liabilities	1,152	1,434
Interest Rate Contract [Member] | Level 2 [Member]
Derivative assets	947	1,391
Derivative liabilities	1,151	1,433
Interest Rate Contract [Member] | Level 3 [Member]
Derivative assets	47	55
Derivative liabilities	1	1
Foreign Exchange Contracts [Member]
Derivative assets	2	4
Derivative liabilities	4	3
Foreign Exchange Contracts [Member] | Level 2 [Member]
Derivative assets	2	4
Derivative liabilities	$ 4	$ 3