Credit Quality (Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment) (Detail) - USD ($) $ in Millions		Jun. 30, 2018		Mar. 31, 2018	[1]	Dec. 31, 2017		Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	[2]
FinancingReceivableAllowanceForCreditLossesLineItems
Individually evaluated for impairment		$ 178	[1]			$ 200	[2]
Collectively evaluated for impairment		791	[1]			876	[2]
Unallocated		108	[1]			120	[2]
Total allowance for loan and lease losses		1,077	[1],[3]	$ 1,138	[3]	1,196	[2],[3]	$ 1,226	$ 1,238	$ 1,253	[3]
Individually evaluated for impairment		1,485	[4]			1,545	[5]
Collectively evaluated for impairment		90,285	[4]			90,286	[5]
Loans acquired with deteriorated credit quality	[5]					2
Total portfolio loans and leases		91,770	[4],[6]			91,833	[5],[7]
Commercial Portfolio Segment
FinancingReceivableAllowanceForCreditLossesLineItems
Individually evaluated for impairment		75	[1]			94	[2]
Collectively evaluated for impairment		579	[1]			659	[2]
Unallocated		0	[1]			0	[2]
Total allowance for loan and lease losses		654	[1]	713		753	[2]	817	826	831
Individually evaluated for impairment		400	[4]			560	[5]
Collectively evaluated for impairment		56,103	[4]			55,835	[5]
Loans acquired with deteriorated credit quality	[5]					0
Total portfolio loans and leases		56,503	[4]			56,395	[5]
Residential Mortgage Loans
FinancingReceivableAllowanceForCreditLossesLineItems
Individually evaluated for impairment		65	[1]			64	[2]
Collectively evaluated for impairment		21	[1]			25	[2]
Unallocated		0	[1]			0	[2]
Total allowance for loan and lease losses		86	[1]	89		89	[2]	93	96	96
Individually evaluated for impairment		788	[4]			665	[5]
Collectively evaluated for impairment		14,690	[4]			14,787	[5]
Loans acquired with deteriorated credit quality	[5]					2
Total portfolio loans and leases		15,478	[4]			15,454	[5]
Consumer Portfolio Segment
FinancingReceivableAllowanceForCreditLossesLineItems
Individually evaluated for impairment		38	[1]			42	[2]
Collectively evaluated for impairment		191	[1]			192	[2]
Unallocated		0	[1]			0	[2]
Total allowance for loan and lease losses		229	[1]	222		234	[2]	206	204	214
Individually evaluated for impairment		297	[4]			320	[5]
Collectively evaluated for impairment		19,492	[4]			19,664	[5]
Loans acquired with deteriorated credit quality	[5]					0
Total portfolio loans and leases		19,789	[4]			19,984	[5]
Unallocated
FinancingReceivableAllowanceForCreditLossesLineItems
Individually evaluated for impairment		0	[1]			0	[2]
Collectively evaluated for impairment		0	[1]			0	[2]
Unallocated		108	[1]			120	[2]
Total allowance for loan and lease losses		108	[1]	$ 114		120	[2]	$ 110	$ 112	$ 112
Individually evaluated for impairment		0	[4]			0	[5]
Collectively evaluated for impairment		0	[4]			0	[5]
Loans acquired with deteriorated credit quality	[5]					0
Total portfolio loans and leases		$ 0	[4]			$ 0	[5]

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

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

[3] 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 .

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

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

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