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Amounts charged-off on TDRs.

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Financing Receivable, Collateral Dependent Loans

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Investment recorded represented by troubled debt restructuring in the current period.

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Maximum exposure to credit risk of loans or receivables.

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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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Amount excluding accrued interest, of allowance for credit loss on financing receivable.

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Amount, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

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Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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

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The sum of the carrying amounts, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of related debt obligations, primarily secured borrowings and repurchase agreements, and for which the transferees are not permitted to sell or re-pledge them to an unrelated party.

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Loans and Allowance for Loan Losses - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Jan. 01, 2022	Dec. 31, 2021	Dec. 31, 2020
Changes in lines of credit,resrticted to commercial exposure
Loan syndications, amount	$ 100,000,000
Mortgage loans partially or wholly-owned by others and serviced by the Company	91,200,000			$ 95,800,000
Financing receivable, allowance for credit loss, excluding accrued interest	124,166,000	$ 111,080,000		97,787,000	$ 113,031,000
Total loans	$ 12,182,203,000			12,281,510,000
Maximum number of days required for special mention	90 days
Amount of specific reserve associated with the TDR	$ 2,500,000			3,400,000
Amount of additional commitments to lend to borrowers who have been a party to a TDR	0			0
Outstanding recorded investment of loans that were new to troubled debt restructuring	800,000			800,000
Amounts charged-off on TDRs	0	$ 0
Residential Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, collateral dependent loans	800,000			600,000
Commercial Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, collateral dependent loans	11,600,000			13,100,000
Cumulative effect accounting adjustment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest				27,086,000
CARES Act \| Payment Deferral
Changes in lines of credit,resrticted to commercial exposure
Loans which underwent a modification, CARES Act	49,000,000			106,700,000
Unfunded Loan Commitment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest	10,400,000		$ 11,100,000
Unfunded Loan Commitment \| Cumulative effect accounting adjustment
Changes in lines of credit,resrticted to commercial exposure
Financing receivable, allowance for credit loss, excluding accrued interest			$ 1,000,000
Federal Home Loan Bank Advances
Changes in lines of credit,resrticted to commercial exposure
Carrying value of loans pledged to secure advances from federal banks	3,000,000,000			2,600,000,000
Funds borrowed from federal banks	13,700,000			14,000,000
Federal Reserve Bank Advances
Changes in lines of credit,resrticted to commercial exposure
Carrying value of loans pledged to secure advances from federal banks	799,900,000			784,000,000
Funds borrowed from federal banks	0			0
Nonperforming Loans
Changes in lines of credit,resrticted to commercial exposure
Total loans				9,040,062,000
Unrated
Changes in lines of credit,resrticted to commercial exposure
Lines of credit, exposure	100,000
Unrated \| Nonperforming Loans
Changes in lines of credit,resrticted to commercial exposure
Total loans				872,544,000
Unrated \| Nonperforming Loans \| Paycheck Protection Program \| Commercial Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Total loans	51,700,000			112,800,000
Unrated \| Nonperforming Loans \| Paycheck Protection Program \| Business Banking
Changes in lines of credit,resrticted to commercial exposure
Total loans	89,500,000			218,600,000
Unrated \| Line of Credit \| Commercial Portfolio Segment
Changes in lines of credit,resrticted to commercial exposure
Lines of credit, exposure	1,000,000
Unrated \| Line of Credit \| Business Banking
Changes in lines of credit,resrticted to commercial exposure
Lines of credit, exposure	1,000,000
Loss
Changes in lines of credit,resrticted to commercial exposure
Loans, net of allowance for loan losses	$ 0
Loss \| Nonperforming Loans
Changes in lines of credit,resrticted to commercial exposure
Total loans				$ 0