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v3.21.2

Loans (Narrative) (Details) | 9 Months Ended | 12 Months Ended | 21 Months Ended |
--- | --- | --- | --- | ---
Sep. 30, 2021 USD ($) Contract | Sep. 30, 2020 Contract | Dec. 31, 2020 USD ($) | Sep. 30, 2021 USD ($) | Dec. 27, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans held for sale | $ 5,916,000 |  | $ 4,305,000 | $ 5,916,000 |
Investment securities, past due | 3,609,791,000 |  | 3,557,908,000 | 3,609,791,000 |
Loans | 3,608,455,000 |  | 3,542,718,000 | 3,608,455,000 |
Past due greater than 90 days and still accruing interest | 0 |  | 0 | $ 0 |
Interest income on nonaccrual loans | $ 0 |  | 0 |  |
Number of loans modified as TDR | Contract | 0 | 0 |  |  |
Number of loans modified as TDR that defaulted within the previous 12 months | Contract | 0 | 0 |  |  |
Days past due when loans are generally placed on nonaccrual status, in days | 90 days | 90 days |  |  |
ASU 2016-13 [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Change in Accounting Principle, Accounting Standards Update, Adopted | true |  |  | true |
Change in Accounting Principle, Accounting Standards Update, Adoption Date | Jan. 01, 2020 |  |  | Jan. 01, 2020 |
Change in retained earnings |  |  |  | $ 8,700,000 |
Increase (decrease) in deferred tax assets |  |  |  | 3,000,000.0 |
ASU 2016-13 [Member] | Held To Maturity Investment Securities [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Increase in the allowance for credit losses on loans |  |  |  | 14,000 |
Other Assets [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Accrued interest receivable | $ 12,800,000 |  | 13,600,000 | 12,800,000 |
Deferral [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans | 61,400,000 |  | 113,000,000.0 | 61,400,000 |
30 to 59 Days Past Due [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Investment securities, past due | 16,943,000 |  | 6,209,000 | 16,943,000 |
Paycheck Protection Program [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans | 121,400,000 |  | 253,100,000 | 121,400,000 | $ 284,000,000,000
COVID-19 [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans |  |  | 532,400,000 |  |
Residential Real Estate Loans [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Loans held for sale |  |  | 4,300,000 |  |
Investment securities, past due | 570,435,000 |  | 586,537,000 | 570,435,000 |
Residential Real Estate Loans [Member] | 30 to 59 Days Past Due [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Investment securities, past due | 543,000 |  | 984,000 | 543,000 |
Consumer Overdrafts [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Past due greater than 90 days and still accruing interest | 1,000 |  | 231,000 | 1,000 |
Commercial Business [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Investment securities, past due | 689,819,000 |  | 798,409,000 | 689,819,000 |
Commercial Business [Member] | 30 to 59 Days Past Due [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Investment securities, past due | 11,489,000 |  | $ 264,000 | 11,489,000 |
Commercial Business [Member] | Paycheck Protection Program [Member] | 30 to 59 Days Past Due [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Investment securities, past due | $ 11,400,000 |  |  | 11,400,000 |
Loans [Member] | ASU 2016-13 [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Increase in the allowance for credit losses on loans |  |  |  | 9,600,000 |
Unfunded Commitments [Member] | ASU 2016-13 [Member] |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |
Increase in the allowance for credit losses on loans |  |  |  | $ 2,100,000 |

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