Loans and Leases and the Allowance for Credit Losses - Loan Modification Activities to Borrowers Experiencing Financial Difficulty on Financing Receivables (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 330,000	$ 592,000	$ 996,000	$ 1,198,000
Percent of Total Loan Class	0.24%	0.45%	0.73%	0.91%
Commercial and industrial
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 117,000	$ 41,000	$ 270,000	$ 127,000
Percent of Total Loan Class	0.19%	0.07%	0.44%	0.23%
Commercial | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 164,000	$ 278,000	$ 425,000	$ 423,000
Percent of Total Loan Class	0.73%	1.07%	1.90%	1.63%
Residential builder and developer | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 2,000	$ 0	$ 13,000	$ 71,000
Percent of Total Loan Class	0.17%	0.00%	1.27%	6.42%
Other commercial construction | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 2,000	$ 216,000	$ 139,000	$ 440,000
Percent of Total Loan Class	0.03%	3.20%	2.62%	6.54%
Residential | Residential Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 42,000	$ 55,000	$ 139,000	$ 125,000
Percent of Total Loan Class	0.19%	0.24%	0.63%	0.56%
Residential — limited documentation | Residential Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 3,000	$ 2,000	$ 7,000	$ 11,000
Percent of Total Loan Class	0.41%	0.18%	0.86%	1.11%
Home equity lines and loans | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 0	$ 0	$ 2,000	$ 1,000
Percent of Total Loan Class	0.00%	0.00%	0.04%	0.02%
Recreational finance | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 0	$ 0	$ 1,000	$ 0
Percent of Total Loan Class	0.00%	0.00%	0.01%	0.00%
Automobile | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 0	$ 0	$ 0	$ 0
Percent of Total Loan Class	0.00%	0.00%	0.00%	0.00%
Other | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 0	$ 0	$ 0	$ 0
Percent of Total Loan Class	0.00%	0.00%	0.00%	0.00%
Term Extension
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 295,000	$ 576,000	$ 892,000	$ 1,137,000
Term Extension | Commercial and industrial
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	92,000	40,000	190,000	115,000
Term Extension | Commercial | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	163,000	272,000	420,000	409,000
Term Extension | Residential builder and developer | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	2,000	0	13,000	70,000
Term Extension | Other commercial construction | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	2,000	216,000	139,000	432,000
Term Extension | Residential | Residential Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	34,000	47,000	123,000	104,000
Term Extension | Residential — limited documentation | Residential Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	2,000	1,000	5,000	6,000
Term Extension | Home equity lines and loans | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	1,000	1,000
Term Extension | Recreational finance | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	1,000	0
Term Extension | Automobile | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Term Extension | Other | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Other (a)
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	29,000	8,000	91,000	32,000
Other (a) | Commercial and industrial
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	23,000	0	78,000	10,000
Other (a) | Commercial | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	1,000	0	1,000	0
Other (a) | Residential builder and developer | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	1,000
Other (a) | Other commercial construction | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Other (a) | Residential | Residential Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	4,000	7,000	10,000	17,000
Other (a) | Residential — limited documentation | Residential Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	1,000	1,000	2,000	4,000
Other (a) | Home equity lines and loans | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Other (a) | Recreational finance | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Other (a) | Automobile | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Other (a) | Other | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Combination of Modification Types
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	6,000	8,000	13,000	29,000
Combination of Modification Types | Commercial and industrial
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	2,000	1,000	2,000	2,000
Combination of Modification Types | Commercial | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	6,000	4,000	14,000
Combination of Modification Types | Residential builder and developer | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Combination of Modification Types | Other commercial construction | Commercial Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	8,000
Combination of Modification Types | Residential | Residential Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	4,000	1,000	6,000	4,000
Combination of Modification Types | Residential — limited documentation | Residential Real Estate
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	1,000
Combination of Modification Types | Home equity lines and loans | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	1,000	0
Combination of Modification Types | Recreational finance | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Combination of Modification Types | Automobile | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	0	0	0	0
Combination of Modification Types | Other | Consumer:
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]
Modified in period	$ 0	$ 0	$ 0	$ 0