Fair Value Disclosures (Roll Forward of Level 3 Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Mortgage banking income	$ (840)	$ (436)	$ (521)
Trading [Member]
Beginning balance	1	11	93
Interest income	0	0	0
Mortgage banking income	0	0	0
Other noninterest income	0	(3)	(1)
Included in unrealized net holding gains (losses) in OCI (loss)	0	0	0
Purchases	4	7
Issuances	0	0
Sales	(4)	(14)
Settlements	0	0
Purchases, issuances and settlements			(5)
Transfers into Level 3		0
Transfers out of Level 3		0
Transfers in and/or out of Level 3			(76)
Ending balance	1	1	11
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	0	0	(2)
States and Political Subdivisions [Member]
Beginning balance		119	210
Interest income		0	0
Mortgage banking income		0	0
Other noninterest income		0	0
Included in unrealized net holding gains (losses) in OCI (loss)		(9)	12
Purchases		0
Issuances		0
Sales		0
Settlements		(53)
Purchases, issuances and settlements			(87)
Transfers into Level 3		0
Transfers out of Level 3		(57)
Transfers in and/or out of Level 3			(16)
Ending balance		0	119
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period		0	0
Other Securities [Member]
Beginning balance		7	9
Interest income		0	0
Mortgage banking income		0	0
Other noninterest income		0	0
Included in unrealized net holding gains (losses) in OCI (loss)		(1)	(1)
Purchases		0
Issuances		0
Sales		0
Settlements		(1)
Purchases, issuances and settlements			(1)
Transfers into Level 3		0
Transfers out of Level 3		(5)
Transfers in and/or out of Level 3			0
Ending balance		0	7
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period		0	0
Covered Securities [Member]
Beginning balance	984	954	668
Interest income	48	54	61
Mortgage banking income	0	0	0
Other noninterest income	0	0	0
Included in unrealized net holding gains (losses) in OCI (loss)	88	24	225
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(126)	(48)
Purchases, issuances and settlements			0
Transfers into Level 3		0
Transfers out of Level 3		0
Transfers in and/or out of Level 3			0
Ending balance	994	984	954
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	48	54	61
Residential MSR [Member]
Beginning balance	563	830	832
Interest income	0	0	0
Mortgage banking income	(32)	(341)	(138)
Other noninterest income	0	0	0
Included in unrealized net holding gains (losses) in OCI (loss)	0	0	0
Purchases	0	0
Issuances	270	225
Sales	0	0
Settlements	(174)	(151)
Purchases, issuances and settlements			136
Transfers into Level 3		0
Transfers out of Level 3		0
Transfers in and/or out of Level 3			0
Ending balance	627	563	830
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	(32)	(341)	(138)
Net Derivatives [Member]
Beginning balance	59	(25)	(20)
Interest income	0	0	0
Mortgage banking income	458	151	246
Other noninterest income	0	0	0
Included in unrealized net holding gains (losses) in OCI (loss)	0	0	0
Purchases	0	0
Issuances	308	110
Sales	0	0
Settlements	(771)	(177)
Purchases, issuances and settlements			(251)
Transfers into Level 3		0
Transfers out of Level 3		0
Transfers in and/or out of Level 3			0
Ending balance	54	59	(25)
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	54	59	(25)
Private Equity and Similar Investments
Beginning balance	261	266	281
Interest income	0	0	0
Mortgage banking income	0	0	0
Other noninterest income	21	64	35
Included in unrealized net holding gains (losses) in OCI (loss)	0	0	0
Purchases	101	61
Issuances	0	0
Sales	(59)	(112)
Settlements	(1)	(15)
Purchases, issuances and settlements			(50)
Transfers into Level 3		1
Transfers out of Level 3		(4)
Transfers in and/or out of Level 3			0
Ending balance	323	261	266
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	$ 12	$ 39	$ 9