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Amount of interest income on financing receivable on nonaccrual status.

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Loans and Leases - Narrative (Detail) $ in Thousands	12 Months Ended
Loans and Leases - Narrative (Detail) $ in Thousands	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized premiums	$ (1,800)	$ (33,800)
Interest receivable	265,000	270,400
Loans and leases, net	51,815,602	50,090,315
Interest on non-accrual loans that would have been recorded as additional interest income	$ 45,400	$ 22,900	$ 16,900
Number of Contracts \| loan			107
Funds held in escrow
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified loans			$ 3,600
Number of Contracts \| loan			3
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified loans			$ 600
Number of Contracts \| loan			2
Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified loans			$ 300
Number of Contracts \| loan			2
Commercial portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Write-down of TDR's			$ 14,700
Consumer portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Write-down of TDR's			$ 300
Consumer portfolio \| Residential \| Term Extension
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts \| loan			2
Prepaid expenses \| Customer Concentration Risk \| Loans and Finance Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration of credit risk	40.70%	41.70%
Commercial non-mortgage \| Customer Concentration Risk \| Loans and Finance Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration of credit risk	34.40%	33.30%
Commercial non-mortgage \| Term Extension
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified loans	$ 17,800
Collateral Pledged \| Commercial portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	139,500	$ 66,100
Collateral Pledged \| Consumer portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	29,100	22,700
Collateral Pledged \| Asset Pledged as Collateral \| Federal Home Loan Bank Certificates and Obligations (FHLB)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net	17,900,000
Collateral Pledged \| Asset Pledged as Collateral \| Federal Reserve Bank Certificates And Obligations (FRB)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net	2,900,000
Collateral Value
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	$ 200,100	$ 93,700