Fair Value Disclosures (Roll Forward of Level 3 Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Mortgage banking income	$ (211)	$ (123)	$ (609)	$ (301)
Trading [Member]
Beginning balance	1	1	1	11
Interest income	0	0	0	0
Mortgage banking income	0	0	0	0
Other noninterest income	0	0	0	(3)
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	0	0	0	0
Purchases	3	5	3	7
Issuances	0	0	0	0
Sales	0	(2)	0	(11)
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	4	4	4	4
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	0	0	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				(53)
Transfers into Level 3				0
Transfers out of Level 3				(57)
Ending balance		0		0
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period				0
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		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	982	1,063	984	954
Interest income	13	11	31	37
Mortgage banking income	0	0	0	0
Other noninterest income	0	0	0	0
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	9	53	49	136
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(32)	(23)	(92)	(23)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	972	1,104	972	1,104
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	13	11	31	37
Residential Mortgage Servicing Rights [Member]
Beginning balance	578	879	563	830
Interest income	0	0	0	0
Mortgage banking income	(76)	(345)	(195)	(422)
Other noninterest income	0	0	0	0
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	0	0	0	0
Purchases	0	0	0	0
Issuances	61	39	195	165
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	563	573	563	573
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	(29)	(299)	(67)	(319)
Net Derivatives [Member]
Beginning balance	68	3	59	(25)
Interest income	0	0	0	0
Mortgage banking income	124	54	309	80
Other noninterest income	0	0	0	0
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	0	0	0	0
Purchases	0	0	0	0
Issuances	106	46	244	67
Sales	0	0	0	0
Settlements	(170)	(31)	(484)	(50)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	128	72	128	72
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	128	72	128	72
Private Equity and Similar Investments [Member]
Beginning balance	301	247	261	266
Interest income	0	0	0	0
Mortgage banking income	0	0	0	0
Other noninterest income	6	19	10	34
Included in unrealized net holding gains (losses) in other comprehensive income (loss)	0	0	0	0
Purchases	12	34	64	46
Issuances	0	0	0	0
Sales	(7)	(19)	(25)	(55)
Settlements	(1)	(5)	1	(12)
Transfers into Level 3	0	0	0	1
Transfers out of Level 3	0	0	0	(4)
Ending balance	311	276	311	276
Change in unrealized gains (losses) included in earnings for the period, attributable to assets and liabilities still held at end of period	$ 6	$ 18	$ 13	$ 30