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Borrowings - Narrative (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Debt Instrument [Line Items] |  |  |
Ratio of line of credit to eligible assets | 45.00% |  |
Line of credit | $ 271,800,000 |  |
Ratio of line of credit to total assets | 10.00% |  |
Ratio of eligible assets to borrowing capacity | 45.00% |  |
Additional borrowing capacity | $ 1,220,000,000 |  |
Long-term FHLB advances | $ 14,500,000 | $ 14,800,000 |
Amortization period of FHLB advance | 30 years |  |
Loans pledged as collateral | $ 0 | 0 |
FHLB discount window advances outstanding | 0 | 0 |
Interest paid (less than) | $ 3,813,000 | 6,009,000 | $ 5,640,000
Alaska limit on borrowing, percent of total assets | 35.00% |  |
Alaska limit on borrowing, total assets | $ 948,000,000 | 736,000,000 |
Securities sold under repurchase agreements | 0 | 0 |
Interest expense on deposits, borrowings and junior subordinated debentures | $ 3,779,000 | $ 6,051,000 | $ 5,641,000
Weighted average interest rate | 2.90% | 3.12% | 3.39%
Minimum |  |  |
Debt Instrument [Line Items] |  |  |
Term of FHLB advances | 18 years |  |
Fixed rate of FHLB advance | 1.23% |  |
Maximum |  |  |
Debt Instrument [Line Items] |  |  |
Term of FHLB advances | 20 years |  |
Fixed rate of FHLB advance | 3.25% |  |
Note Agreement With Federal Reserve Bank |  |  |
Debt Instrument [Line Items] |  |  |
Loans pledged as collateral | $ 50,700,000 |  |
Interest paid (less than) | 1,000 | $ 1,000 |
Discount Window |  |  |
Debt Instrument [Line Items] |  |  |
Loans pledged as collateral | 32,200,000 |  |
FHLB and Secured Debt |  |  |
Debt Instrument [Line Items] |  |  |
Interest expense on deposits, borrowings and junior subordinated debentures | $ 320,000 | $ 387,000 | $ 291,000

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