Credit Quality (Summary of Transactions in the ALLL by Portfolio Segment) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses
Balance, Beginning of period		$ 1,253	[1]	$ 1,272		$ 1,322
Losses charged-off		(381)		(456)		(542)
Recoveries of losses previously charged-off		83		94		96
Provision for (benefit from) loan and lease losses		261		343		396
Deconsolidation of a VIE		(20)
Balance, end of period		1,196	[1]	1,253	[1]	1,272
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Balance, Beginning of period		831	[2]	840		875
Losses charged-off		(154)		(232)		(298)
Recoveries of losses previously charged-off		29		42		37
Provision for (benefit from) loan and lease losses		66		181		226
Deconsolidation of a VIE	[3]	(19)
Balance, end of period		753	[4]	831	[2]	840
Residential Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Balance, Beginning of period		96	[2]	100		104
Losses charged-off		(15)		(19)		(28)
Recoveries of losses previously charged-off		8		9		11
Provision for (benefit from) loan and lease losses		0		6		13
Deconsolidation of a VIE	[3]	0
Balance, end of period		89	[4]	96	[2]	100
Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Balance, Beginning of period		214	[2]	217		237
Losses charged-off		(212)		(205)		(216)
Recoveries of losses previously charged-off		46		43		48
Provision for (benefit from) loan and lease losses		186		159		148
Deconsolidation of a VIE	[3]	0
Balance, end of period		234	[4]	214	[2]	217
Unallocated
Financing Receivable, Allowance for Credit Losses
Balance, Beginning of period		112	[2]	115		106
Losses charged-off		0		0		0
Recoveries of losses previously charged-off		0		0		0
Provision for (benefit from) loan and lease losses		9		(3)		9
Deconsolidation of a VIE	[3]	(1)
Balance, end of period		$ 120	[4]	$ 112	[2]	$ 115

[1] Includes $ 0 and $ 85 of cash and due from banks, $ 62 and $ 0 of other short-term investments, $ 1,297 and $ 1,216 of portfolio loans and leases, $ (6) and $ (26) of ALLL, $ 7 and $ 9 of other assets, $ 2 and $ 3 of other liabilities and $ 1,190 and $ 1,094 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2017 and 2016 , respectively. For further information, refer to Note 11 .

[2] Includes $ 2 related to leveraged leases at December 31, 2016 .

[3] (a) Refer to Note 11 for further discussion on the deconsolidation of a VIE.

[4] Includes $ 1 related to leveraged leases at December 31, 2017 .