Loans and Leases - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) Modification	Dec. 31, 2021 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	3,641	2,320
Pre-modification Recorded Investment	$ 276	$ 534
Loans and leases, net of unearned discount	$ 280	$ 529
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	231	348
Pre-modification Recorded Investment	$ 98	$ 205
Loans and leases, net of unearned discount	$ 98	$ 202
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	12	35
Pre-modification Recorded Investment	$ 25	$ 184
Loans and leases, net of unearned discount	$ 25	$ 182
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	3	1
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	274	373
Pre-modification Recorded Investment	$ 71	$ 108
Loans and leases, net of unearned discount	$ 75	$ 108
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	8	21
Pre-modification Recorded Investment	$ 1	$ 3
Loans and leases, net of unearned discount	$ 1	$ 3
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	144	89
Pre-modification Recorded Investment	$ 10	$ 6
Loans and leases, net of unearned discount	$ 10	$ 6
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	729	281
Pre-modification Recorded Investment	$ 28	$ 10
Loans and leases, net of unearned discount	$ 28	$ 10
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	2,092	807
Pre-modification Recorded Investment	$ 42	$ 15
Loans and leases, net of unearned discount	$ 42	$ 15
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	149	362
Pre-modification Recorded Investment	$ 1	$ 3
Loans and leases, net of unearned discount	$ 1	$ 3
Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1	1
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 203	$ 247
Principal Deferral [Member] | Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	58	58
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	9	57
Principal Deferral [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	55	95
Principal Deferral [Member] | Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	1	3
Principal Deferral [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	9	6
Principal Deferral [Member] | Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	28	10
Principal Deferral [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	42	15
Principal Deferral [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	1	3
Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	3	72
Other [Member] | Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	3	45
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount		27
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	74	210
Combination of Concession Types [Member] | Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	37	99
Combination of Concession Types [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	16	98
Combination of Concession Types [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	20	$ 13
Combination of Concession Types [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 1