Credit Quality (Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment) (Parenthetical) (Detail) $ in Millions	3 Months Ended				6 Months Ended				12 Months Ended
	Jun. 30, 2018 USD ($)		Jun. 30, 2017 USD ($)		Jun. 30, 2018 USD ($)		Jun. 30, 2017 USD ($)		Dec. 31, 2017 USD ($)		Mar. 31, 2018 USD ($)	[1],[2]	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	[2],[3]
FinancingReceivableAllowanceForCreditLossesLineItems
Allowance for loan and lease losses	$ 1,077	[1],[2]	$ 1,226		$ 1,077	[1],[2]	$ 1,226		$ 1,196	[2],[3]	$ 1,138		$ 1,238	$ 1,253
Portfolio loans and leases	$ 91,770	[4],[5]			$ 91,770	[4],[5]			91,833	[6],[7]
Number of contracts	2,273	[8],[9],[10],[11]	2,430	[12],[13],[14],[15]	4,544	[8],[9],[10],[11]	4,489	[12],[13],[14],[15]
Recorded investment	$ 1,485	[16]			$ 1,485	[16]			1,545	[17]
Variable Interest Entity, Primary Beneficiary
FinancingReceivableAllowanceForCreditLossesLineItems
Allowance for loan and lease losses	5				5				$ 6
Commercial | Variable Interest Entity, Primary Beneficiary
FinancingReceivableAllowanceForCreditLossesLineItems
Number of contracts									5
Leveraged Leases
FinancingReceivableAllowanceForCreditLossesLineItems
Allowance for loan and lease losses	1				1				$ 1
Portfolio loans and leases	650				650				674
Residential Mortgage Loans
FinancingReceivableAllowanceForCreditLossesLineItems
Portfolio loans and leases at fair value	$ 162				$ 162				$ 137

[1] Includes $ 1 related to leveraged leases at June 30, 2018 .

[2] Includes $ 47 and $ 62 of other short-term investments , $ 908 and $ 1,297 of portfolio loans and leases, $ (5) and $ (6) of ALLL, $ 5 and $ 7 of other assets, $ 2 and $ 2 of other liabilities, and $ 830 and $ 1,190 of long-term debt from consolidated VIEs that are included in their respe ctive captions above at June 30, 2018 and December 31, 2017 , respectively. For further information refer to Note 9 .

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

[4] Excludes $ 162 of residential mortgage loans measured at fair value and includes $ 65 0 of leveraged leases, net of unearned income at June 30, 2018 .

[5] Excludes $ 162 of residential mortgage loans measured at fair value at June 30, 2018 .

[6] Excludes $ 137 of residential mortga ge loans measured at fair value and includes $ 674 of leveraged leases, net of unearned income at December 31, 2017 .

[7] Excludes $ 137 of residential mortgage loans measured at fair value at December 31, 2017 .

[8] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[9] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[10] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .

[11] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .

[12] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[13] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[14] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .

[15] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .

[16] Includes $ 104 , $ 773 and $ 251 , respectively, of commercial, residential mortgage and consumer portfolio TDRs on accrual status and $ 173 , $ 15 an d $ 46 , respectively, of commercial, residential mortgage and consumer portfolio TDRs on nonaccrual status at June 30, 2018 .

[17] Includes $ 249 , $ 652 and $ 275 , respectively, of commercial, residential mortgage and consumer portfolio TDR s on accrual status and $ 150 , $ 13 and $ 45 , respectively , of commercial, residential mortgage and consumer portfolio TDRs on nonaccrual status at December 31, 2017 .