Parent Company Financial Statements (Condensed Statement of Cash Flow - Parent Company Only) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Operating Activities
Net income (loss)	$ 1,564		$ 1,712		$ 1,481
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
(Benefit from) provision for deferred income taxes	(148)		(71)		79
Net change in undistributed earnings	66		63		48
Net change in:
Other assets	351		94		(221)
Accrued expenses and other liabilities	(157)		327		1
Net Cash Provided by (Used in) Operating Activities	2,114		2,418		2,076
Net change in:
Other short-term investments	(83)		5,243		(2,798)
Net Cash Provided by (Used in) Investing Activities	(2,887)		(3,931)		(8,938)
Financing Activities
Net change in other short-term borrowings	2,028		(49)		176
Proceeds from issuance of long-term debt	3,735		3,091		6,570
Repayment of long-term debt	5,119		2,205		1,399
Dividends paid on common shares	402		422		423
Dividends paid on preferred shares	52		75		67
Issuance of preferred stock	0		0		297
Repurchase of treasury stock and related forward contract	661		850		654
Other, net	(31)		(28)		(22)
Net Cash Provided (Used in) Provided by Financing Activities	625		962		6,775
Net (Decrease) Increase in Cash	(148)		(551)		(87)
Cash and Due from Banks at Beginning of Period	2,540	[1]	3,091		3,178
Cash and Due from Banks at End of Period	2,392	[1]	2,540	[1]	3,091
Parent Company Only
Operating Activities
Net income (loss)	1,564		1,712		1,481
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
(Benefit from) provision for deferred income taxes	0		(4)		(1)
Net change in undistributed earnings	214		(788)		(491)
Net change in:
Other assets	14		(18)		9
Accrued expenses and other liabilities	(35)		31		(41)
Net Cash Provided by (Used in) Operating Activities	1,757		933		957
Net change in:
Other short-term investments	654		(539)		(684)
Loans to subsidiaries	13		2		(10)
Net Cash Provided by (Used in) Investing Activities	667		(537)		(694)
Financing Activities
Net change in other short-term borrowings	(60)		(22)		115
Proceeds from issuance of long-term debt	0		1,099		499
Repayment of long-term debt	(1,250)		0		0
Dividends paid on common shares	(402)		(422)		(423)
Dividends paid on preferred shares	(52)		(75)		(67)
Issuance of preferred stock	0		0		297
Repurchase of treasury stock and related forward contract	(661)		(850)		(654)
Other, net	3		2		(30)
Net Cash Provided (Used in) Provided by Financing Activities	(2,422)		(268)		(263)
Net (Decrease) Increase in Cash	2		128		0
Cash and Due from Banks at Beginning of Period	128		0		0
Cash and Due from Banks at End of Period	$ 130		$ 128		$ 0

[1] Includes $ 85 and $ 152 of cash and due from banks, $ 1,216 and $ 2,537 of portfolio loans and leases, $ (26) and $ (28) of ALLL, $ 9 and $ 14 of other assets, $ 3 and $ 3 of other liabilities and $ 1,094 and $ 2,487 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2016 and 2015 , respectively. For further information, refer to Note 11.