Fair Value Disclosures (Roll Forward of Level 3 Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Mortgage banking income	$ (216)	$ (95)
Trading [Member]
Beginning balance	1	11
Interest income	0	0
Mortgage banking income	0	0
Other noninterest income	0	(3)
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	(7)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	1	1
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period.	0	0
States and Political Subdivisions [Member]
Beginning balance		119
Interest income		0
Mortgage banking income		0
Other noninterest income		0
Included in unrealized net holding gains (losses) in other comprehensive income (loss)		(9)
Purchases		0
Issuances		0
Sales		0
Settlements		(1)
Transfers into Level 3		0
Transfers out of Level 3		(57)
Ending balance		52
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period.		0
Equity and Other Securities [Member]
Beginning balance		7
Interest income		0
Mortgage banking income		0
Other noninterest income		0
Included in unrealized net holding gains (losses) in other comprehensive income (loss)		(1)
Purchases		0
Issuances		0
Sales		0
Settlements		(1)
Transfers into Level 3		0
Transfers out of Level 3		(5)
Ending balance		0
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period.		0
Covered Securities [Member]
Beginning balance	984	954
Interest income	4	18
Mortgage banking income	0	0
Other noninterest income	0	0
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	62	87
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(27)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	1,023	1,059
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period.	4	18
Residential Mortgage Servicing Rights [Member]
Beginning balance	563	830
Interest income	0	0
Mortgage banking income	49	12
Other noninterest income	0	0
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	0	0
Purchases	0	0
Issuances	84	86
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	696	928
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period.	92	40
Net Derivatives [Member]
Beginning balance	59	(25)
Interest income	0	0
Mortgage banking income	96	(17)
Other noninterest income	0	0
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	0	0
Purchases	0	0
Issuances	61	11
Sales	0	0
Settlements	(186)	38
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	30	7
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period.	30	7
Venture Capital and Similar Investments [Member]
Beginning balance	261	266
Interest income	0	0
Mortgage banking income	0	0
Other noninterest income	5	8
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	0	0
Purchases	24	5
Issuances	0	0
Sales	(12)	(6)
Settlements	3	(1)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	281	272
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period.	$ 9	$ 7