Condensed Statement of Cash Flow - Parent Company Only (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Operating Activities
Net income (loss)	$ 1,712		$ 1,481		$ 1,836
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
(Benefit from) provision for deferred income taxes	(71)		79		253
Net change in undistributed earnings	63		48		77
Net change in:
Other assets	94		(221)		(672)
Accrued expenses and other liabilities	327		1		8
Net Cash Provided by (Used in) Operating Activities	2,418		2,076		4,595
Net change in:
Other short-term investments	5,243		(2,798)		(2,695)
Net Cash (Used in) Provided by Investing Activities	(3,931)		(8,938)		(10,184)
Financing Activities
Net change in other short-term borrowings	(49)		176		(4,900)
Proceeds from issuance of long-term debt	3,091		6,570		5,044
Repayment of long-term debt	2,205		1,399		2,225
Dividends paid on common shares	422		423		393
Dividends paid on preferred shares	75		67		37
Issuance of preferred shares			297		1,034
Repurchase of treasury shares and related forward contract	850		654		1,320
Other	(28)		(22)		(17)
Net Cash Used In Financing Activities	962		6,775		6,326
Net (Decrease) Increase in Cash	(551)		(87)		737
Cash and Due from Banks at Beginning of Period	3,091	[1]	3,178		2,441
Cash and Due from Banks at End of Period	2,540	[1]	3,091	[1]	3,178
Parent Company Only
Operating Activities
Net income (loss)	1,712		1,481		1,836
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
(Benefit from) provision for deferred income taxes	(4)		(1)		(1)
Net change in undistributed earnings	(788)		(491)		(1,103)
Net change in:
Other assets	(19)		8		13
Accrued expenses and other liabilities	32		(40)		(28)
Net Cash Provided by (Used in) Operating Activities	933		957		717
Net change in:
Other short-term investments	(539)		(684)		976
Loans to subsidiaries	2		(10)		47
Net Cash (Used in) Provided by Investing Activities	(537)		(694)		1,023
Financing Activities
Net change in other short-term borrowings	(22)		115		(255)
Proceeds from issuance of long-term debt	1,099		499		750
Repayment of long-term debt					(1,500)
Dividends paid on common shares	(422)		(423)		(393)
Dividends paid on preferred shares	(75)		(67)		(37)
Issuance of preferred shares			297		1,034
Repurchase of treasury shares and related forward contract	(850)		(654)		(1,320)
Other	2		(30)		(19)
Net Cash Used In Financing Activities	(268)		$ (263)		$ (1,740)
Net (Decrease) Increase in Cash	128
Cash and Due from Banks at End of Period	$ 128

[1] Includes $152 and $179 of cash and due from banks, $2,537 and $3,378 of portfolio loans and leases, $(28) and $(22) of ALLL, $20 and $25 of other assets, $3 and $5 of other liabilities and $2,493 and $3,434 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2015 and 2014, respectively. For further information, refer to Note 11.