Loans and Leases and the Allowance for Credit Losses - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) Modification	Mar. 31, 2021 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	935	855
Pre-modification Recorded Investment	$ 61,456	$ 131,632
Loans and leases, net of unearned discount	62,294	129,961
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	46,178	85,516
Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	2,155	2,214
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 13,961	$ 42,231
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	37	93
Pre-modification Recorded Investment	$ 10,003	$ 53,733
Loans and leases, net of unearned discount	9,754	53,157
Commercial, Financial, Leasing, etc. [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	6,920	24,653
Commercial, Financial, Leasing, etc. [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	54
Commercial, Financial, Leasing, etc. [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 2,780	$ 28,504
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	17	33
Pre-modification Recorded Investment	$ 7,582	$ 26,870
Loans and leases, net of unearned discount	7,332	25,796
Commercial Real Estate [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	4,376	11,160
Commercial Real Estate [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	2,101	2,214
Commercial Real Estate [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 855	$ 12,422
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	97	123
Pre-modification Recorded Investment	$ 24,051	$ 39,583
Loans and leases, net of unearned discount	25,404	39,674
Residential [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	15,443	38,557
Residential [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 9,961	$ 1,117
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	35	26
Pre-modification Recorded Investment	$ 2,150	$ 1,715
Loans and leases, net of unearned discount	2,160	1,660
Home Equity Lines and Loans [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	1,988	1,486
Home Equity Lines and Loans [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 172	$ 174
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	177	72
Pre-modification Recorded Investment	$ 5,997	$ 2,212
Loans and leases, net of unearned discount	5,990	2,212
Recreational Finance [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 5,990	$ 2,212
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	534	276
Pre-modification Recorded Investment	$ 10,263	$ 4,969
Loans and leases, net of unearned discount	10,233	4,969
Automobile [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 10,233	4,955
Automobile [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount		$ 14
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	33	222
Pre-modification Recorded Investment	$ 334	$ 1,434
Loans and leases, net of unearned discount	334	1,434
Other [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 334	$ 1,434
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	5	10
Pre-modification Recorded Investment	$ 1,076	$ 1,116
Loans and leases, net of unearned discount	1,087	1,059
Residential Limited Documentation [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	894	$ 1,059
Residential Limited Documentation [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 193