Credit Quality (Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment) (Detail) - USD ($) $ in Millions	Mar. 31, 2018		Dec. 31, 2017		Mar. 31, 2017	Dec. 31, 2016	[2]
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	$ 217	[1]	$ 200	[2]
Collectively evaluated for impairment	807	[1]	876	[2]
Unallocated	114	[1]	120	[2]
Total allowance for loan and lease losses	1,138	[1],[3]	1,196	[2],[3]	$ 1,238	$ 1,253	[3]
Individually evaluated for impairment	1,547	[4]	1,545	[5]
Collectively evaluated for impairment	90,285	[4]	90,286	[5]
Loans acquired with deteriorated credit quality	2	[4]	2	[5]
Total portfolio loans and leases	91,834	[4],[6]	91,833	[5],[7]
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	113	[1]	94	[2]
Collectively evaluated for impairment	600	[1]	659	[2]
Unallocated	0	[1]	0	[2]
Total allowance for loan and lease losses	713	[1]	753	[2]	826	831
Individually evaluated for impairment	573	[4]	560	[5]
Collectively evaluated for impairment	56,256	[4]	55,835	[5]
Loans acquired with deteriorated credit quality	0	[4]	0	[5]
Total portfolio loans and leases	56,829	[4]	56,395	[5]
Residential Mortgage Loans
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	64	[1]	64	[2]
Collectively evaluated for impairment	25	[1]	25	[2]
Unallocated	0	[1]	0	[2]
Total allowance for loan and lease losses	89	[1]	89	[2]	96	96
Individually evaluated for impairment	666	[4]	665	[5]
Collectively evaluated for impairment	14,759	[4]	14,787	[5]
Loans acquired with deteriorated credit quality	2	[4]	2	[5]
Total portfolio loans and leases	15,427	[4]	15,454	[5]
Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	40	[1]	42	[2]
Collectively evaluated for impairment	182	[1]	192	[2]
Unallocated	0	[1]	0	[2]
Total allowance for loan and lease losses	222	[1]	234	[2]	204	214
Individually evaluated for impairment	308	[4]	320	[5]
Collectively evaluated for impairment	19,270	[4]	19,664	[5]
Loans acquired with deteriorated credit quality	0	[4]	0	[5]
Total portfolio loans and leases	19,578	[4]	19,984	[5]
Unallocated
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	0	[1]	0	[2]
Collectively evaluated for impairment	0	[1]	0	[2]
Unallocated	114	[1]	120	[2]
Total allowance for loan and lease losses	114	[1]	120	[2]	$ 112	$ 112
Individually evaluated for impairment	0	[4]	0	[5]
Collectively evaluated for impairment	0	[4]	0	[5]
Loans acquired with deteriorated credit quality	0	[4]	0	[5]
Total portfolio loans and leases	$ 0	[4]	$ 0	[5]

[1] Includes $ 1 related to leveraged leases at March 31, 2018 .

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

[3] Includes $ 66 and $ 62 of other short-term investments , $ 1,135 and $ 1,297 of portfolio loans and leases, $ (6) and $ (6) of ALLL, $ 6 and $ 7 of other assets, $ 2 and $ 2 of other liabilities, and $ 1,031 and $ 1,190 of long-term debt from consolidated VIEs that are included in their respe ctive captions above at March 31, 2018 and December 31, 2017 , respectively. For further information refer to Note 9 .

[4] Excludes $ 136 of residential mortgage loans measured at fair value and includes $ 670 of leveraged leases, net of unearned income at March 31, 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 $ 136 of residential mortgage loans measured at fair value at March 31, 2018 .

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