Consumer Credit Exposures Period Past Due Required To Classify Loans As Special Mention Maximum.

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Maximum exposure to credit risk of loans or receivables.

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Mortgage Loans In Process Of Foreclosure, Number

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Maximum potential amount of future undiscounted payments that could be required under the credit derivative, before reduction for potential recoveries under recourse or collateralization provisions.

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

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Amortized cost excluding accrued interest, after allowance for credit loss, of financing receivable. Excludes net investment in lease.

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Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

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Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

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Amount excluding accrued interest, of increase in financing receivable from purchase. Excludes net investment in lease.

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Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

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The aggregate amount of the participating mortgage obligation at the end of the accounting period.

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Loans and Allowance for Credit Losses - Narrative (Details)	3 Months Ended
	Mar. 31, 2024 USD ($) loan	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) loan	Dec. 31, 2022 USD ($)
Changes in lines of credit,resrticted to commercial exposure
Loan syndications, amount	$ 100,000,000
Financing receivable, excluding accrued interest, after allowance for credit loss	13,906,610,000		$ 13,799,367,000
Debt, long-term and short-term, combined amount	52,754,000		48,216,000
Mortgage loans partially or wholly-owned by others and serviced by the Company	76,200,000		77,200,000
Loan purchases		$ 32,000,000
Provision for allowance for loan losses	7,451,000	25,000
Partial charge off	8,015,000	911,000
Financing receivable, allowance for credit loss, excluding accrued interest	$ 149,190,000	140,938,000	148,993,000	$ 142,211,000
Maximum number of days required for special mention	90 days
Federal Home Loan Bank Advances \| Asset Pledged as Collateral
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, excluding accrued interest, after allowance for credit loss	$ 4,400,000,000		4,600,000,000
Federal Reserve Bank Advances \| Asset Pledged as Collateral
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, excluding accrued interest, after allowance for credit loss	1,100,000,000		1,100,000,000
Residential Real Estate
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, collateral dependent loans	900,000		800,000
Commercial Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, collateral dependent loans	37,800,000		30,700,000
Cumulative effect accounting adjustment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest				(1,143,000)
Unfunded Loan Commitment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest	12,100,000		14,100,000
Residential real estate \| Residential Real Estate
Changes in lines of credit,resrticted to commercial exposure
Amortized cost of loans purchased	381,200,000		385,500,000
Provision for allowance for loan losses	(40,000)	(165,000)
Partial charge off	10,000	0
Financing receivable, allowance for credit loss, excluding accrued interest	$ 25,935,000	27,130,000	$ 25,954,000	28,129,000
Number of loans in process of foreclosure \| loan	4		2
Mortgage loans in process of foreclosure, amount	$ 400,000		$ 200,000
Residential real estate \| Cumulative effect accounting adjustment \| Residential Real Estate
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest				(849,000)
Consumer home equity \| Consumer Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Provision for allowance for loan losses	91,000	(65,000)
Partial charge off	2,000	7,000
Financing receivable, allowance for credit loss, excluding accrued interest	$ 5,684,000	6,182,000	$ 5,595,000	6,454,000
Number of loans in process of foreclosure \| loan	3		3
Mortgage loans in process of foreclosure, amount	$ 200,000		$ 200,000
Consumer home equity \| Cumulative effect accounting adjustment \| Consumer Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest				(201,000)
Commercial and industrial \| Commercial Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Provision for allowance for loan losses	1,879,000	(116,000)
Partial charge off	0	0
Financing receivable, allowance for credit loss, excluding accrued interest	28,863,000	26,929,000	26,959,000	26,859,000
Commercial and industrial \| Cumulative effect accounting adjustment \| Commercial Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest				47,000
Commercial real estate \| Commercial Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Provision for allowance for loan losses	6,272,000	459,000
Partial charge off	7,250,000	0
Financing receivable, allowance for credit loss, excluding accrued interest	64,629,000	$ 55,193,000	65,475,000	54,730,000
Commercial real estate \| Cumulative effect accounting adjustment \| Commercial Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest				$ 0
Federal Home Loan Bank Advances
Changes in lines of credit,resrticted to commercial exposure
Advance from federal home loan bank	17,600,000		17,700,000
Federal Reserve Bank Advances
Changes in lines of credit,resrticted to commercial exposure
Debt, long-term and short-term, combined amount	0		$ 0
Unrated \| Minimum
Changes in lines of credit,resrticted to commercial exposure
Lines of credit, exposure	100,000
Unrated \| Line of Credit \| Commercial Portfolio Segment \| Maximum
Changes in lines of credit,resrticted to commercial exposure
Lines of credit, exposure	1,500,000
Unrated \| Line of Credit \| Business Banking \| Commercial Portfolio Segment \| Maximum
Changes in lines of credit,resrticted to commercial exposure
Lines of credit, exposure	$ 1,500,000