Condensed Statement of Cash Flow - Parent Company Only (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Operating Activities
Net income (loss)	$ 1,297		$ 753		$ 737
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Provision (benefit) for deferred income taxes	437		176		184
Net change in:
Other assets	(67)		9		826
Accrued taxes, interest and expenses	79		(63)		(1,200)
Net Cash Provided by (Used in) Operating Activities	2,366		3,305		3,794
Capital Contribution To Subsidiaries [Abstract]
Net cash paid in business combinations					(16)
Net change in:
Other short-term investments	(267)		1,861		209
Net Cash (Used in) Provided by Investing Activities	(5,285)		1,708		1,076
Financing Activities
Net change in other short-term borrowings	1,665		38		(8,544)
Proceeds from issuance of long-term debt	1,500		14		527
Repayment of long-term debt	1,607		2,473		3,065
Dividends paid on common shares	192		32		27
Dividends paid on preferred shares	50		205		220
Common stock issued, value	1,648				986
Redemption of Series F preferred shares and related warrants	3,408
Dividends on exchange of preferred stock, Series G					35
Net Cash Used In Financing Activities	3,423		(5,172)		(5,291)
Increase (Decrease) in Cash and Due from Banks	504		(159)		(421)
Cash and Due from Banks at Beginning of Period	2,159	[1]	2,318		2,739
Cash and Due from Banks at End of Period	2,663	[1]	2,159	[1]	2,318
Parent Company [Member]
Operating Activities
Net income (loss)	1,297		753		737
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Provision (benefit) for deferred income taxes	(3)		(2)		2
Undistributed earnings (loss) less dividends from subsidiaries	247		530		(869)
Net change in:
Other assets	39		(6)		83
Accrued taxes, interest and expenses	3		(339)		591
Other, net			(11)		(6)
Net Cash Provided by (Used in) Operating Activities	1,583		925		538
Capital Contribution To Subsidiaries [Abstract]
Bank subsidiaries					(1,600)
Net change in:
Other short-term investments	(635)		(603)		1,158
Loans to subsidiaries	(489)		161		117
Net Cash (Used in) Provided by Investing Activities	(146)		(764)		(559)
Financing Activities
Net change in other short-term borrowings	241		134		(503)
Proceeds from issuance of long-term debt	1,000
Repayment of long-term debt	400				31
Dividends paid on common shares	192		32		27
Dividends paid on preferred shares	50		205		220
Common stock issued, value	1,648				987
Redemption of Series F preferred shares and related warrants	3,688				269
Dividends on exchange of preferred stock, Series G					35
Other, net	(6)				(10)
Net Cash Used In Financing Activities	(1,447)		(103)		(38)
Increase (Decrease) in Cash and Due from Banks	(10)		58		(59)
Cash and Due from Banks at Beginning of Period	60		2		61
Cash and Due from Banks at End of Period	$ 50		$ 60		$ 2

[1] At December 31, 2011 and 2010, includes $30 and $52 of cash, $7 of other short-term investments, $50 and $29 of commercial mortgage loans, $223 and $241 of home equity loans, $259 and $648 of automobile loans, ($10) and ($14) of ALLL, $4 and $7 of other assets, $4 and $12 of other liabilities, $191 and $692 of long-term debt from consolidated VIEs that are included in their respective captions. See Note 11.