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Loans and Allowance for Credit Losses - Allowance for Credit Losses (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2020 | Sep. 30, 2020 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | $ 22,113 | $ 16,677 | $ 16,677 |  |
Accounting Standards Update [Extensible List] |  | us-gaap:AccountingStandardsUpdate201613Member |  | us-gaap:AccountingStandardsUpdate201613Member |
Provision (reversal) - CECL method | (856) |  |  |  |
(Charge-offs) | (1) |  |  |  |
Recoveries | 14 |  |  |  |
Ending balance | 22,874 | $ 22,113 | 22,874 | $ 16,677 |
Beginning balance | 22,113 | 16,677 | 16,677 | 15,821 | $ 15,767
Provision (reversal) - incurred loss method |  | 5,450 | 4,594 | 900 | 0
(Charge-offs) |  | (30) |  | (78) | (5)
Recoveries |  | 16 |  | 34 | 59
Ending balance |  | 22,113 |  | 16,677 | 15,821
Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 1,604 |  |  |  |
Ending balance |  | 1,604 |  |  |
Allowance for credit losses on loans | 748 |  |  |  |
Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 23,717 |  |  |  |
Ending balance |  | 23,717 |  |  |
Commercial | Commercial and industrial |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 2,525 |  |  |  |
Provision (reversal) - CECL method | 269 |  |  |  |
(Charge-offs) | 0 |  |  |  |
Recoveries | 14 |  |  |  |
Ending balance | 2,530 | 2,525 | 2,530 |  |
Beginning balance | 2,525 | 2,334 | 2,334 | 2,436 | 3,654
Provision (reversal) - incurred loss method |  | 208 |  | (49) | (1,232)
(Charge-offs) |  | (30) |  | (75) | (3)
Recoveries |  | 13 |  | 22 | 17
Ending balance |  | 2,525 |  | 2,334 | 2,436
Commercial | Commercial and industrial | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | (278) |  |  |  |
Ending balance |  | (278) |  |  |
Commercial | Commercial and industrial | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 2,247 |  |  |  |
Ending balance |  | 2,247 |  |  |
Commercial real estate | Commercial real estate, owner-occupied |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 3,135 |  |  |  |
Provision (reversal) - CECL method | (495) |  |  |  |
(Charge-offs) | 0 |  |  |  |
Recoveries | 0 |  |  |  |
Ending balance | 2,778 | 3,135 | 2,778 |  |
Beginning balance | 3,135 | 2,462 | 2,462 | 2,407 | 2,294
Provision (reversal) - incurred loss method |  | 673 |  | 55 | 113
(Charge-offs) |  | 0 |  | 0 | 0
Recoveries |  | 0 |  | 0 | 0
Ending balance |  | 3,135 |  | 2,462 | 2,407
Commercial real estate | Commercial real estate, owner-occupied | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 138 |  |  |  |
Ending balance |  | 138 |  |  |
Commercial real estate | Commercial real estate, owner-occupied | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 3,273 |  |  |  |
Ending balance |  | 3,273 |  |  |
Commercial real estate | Commercial real estate, investor-owned |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 11,624 |  |  |  |
Provision (reversal) - CECL method | (697) |  |  |  |
(Charge-offs) | 0 |  |  |  |
Recoveries | 0 |  |  |  |
Ending balance | 12,682 | 11,624 | 12,682 |  |
Beginning balance | 11,624 | 8,483 | 8,483 | 7,703 | 6,475
Provision (reversal) - incurred loss method |  | 3,141 |  | 768 | 1,228
(Charge-offs) |  | 0 |  | 0 | 0
Recoveries |  | 0 |  | 12 | 0
Ending balance |  | 11,624 |  | 8,483 | 7,703
Commercial real estate | Commercial real estate, investor-owned | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 1,755 |  |  |  |
Ending balance |  | 1,755 |  |  |
Commercial real estate | Commercial real estate, investor-owned | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 13,379 |  |  |  |
Ending balance |  | 13,379 |  |  |
Commercial real estate | Construction |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 860 |  |  |  |
Provision (reversal) - CECL method | 496 |  |  |  |
(Charge-offs) | 0 |  |  |  |
Recoveries | 0 |  |  |  |
Ending balance | 1,557 | 860 | 1,557 |  |
Beginning balance | 860 | 638 | 638 | 756 | 681
Provision (reversal) - incurred loss method |  | 219 |  | (118) | 75
(Charge-offs) |  | 0 |  | 0 | 0
Recoveries |  | 3 |  | 0 | 0
Ending balance |  | 860 |  | 638 | 756
Commercial real estate | Construction | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 201 |  |  |  |
Ending balance |  | 201 |  |  |
Commercial real estate | Construction | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 1,061 |  |  |  |
Ending balance |  | 1,061 |  |  |
Residential loans | Home equity |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 1,038 |  |  |  |
Provision (reversal) - CECL method | 61 |  |  |  |
(Charge-offs) | 0 |  |  |  |
Recoveries | 0 |  |  |  |
Ending balance | 738 | 1,038 | 738 |  |
Beginning balance | 1,038 | 850 | 850 | 915 | 1,031
Provision (reversal) - incurred loss method |  | 188 |  | (65) | (116)
(Charge-offs) |  | 0 |  | 0 | 0
Recoveries |  | 0 |  | 0 | 0
Ending balance |  | 1,038 |  | 850 | 915
Residential loans | Home equity | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | (361) |  |  |  |
Ending balance |  | (361) |  |  |
Residential loans | Home equity | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 677 |  |  |  |
Ending balance |  | 677 |  |  |
Residential loans | Other residential |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 1,260 |  |  |  |
Provision (reversal) - CECL method | (50) |  |  |  |
(Charge-offs) | 0 |  |  |  |
Recoveries | 0 |  |  |  |
Ending balance | 998 | 1,260 | 998 |  |
Beginning balance | 1,260 | 973 | 973 | 800 | 536
Provision (reversal) - incurred loss method |  | 287 |  | 173 | 264
(Charge-offs) |  | 0 |  | 0 | 0
Recoveries |  | 0 |  | 0 | 0
Ending balance |  | 1,260 |  | 973 | 800
Residential loans | Other residential | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | (212) |  |  |  |
Ending balance |  | (212) |  |  |
Residential loans | Other residential | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 1,048 |  |  |  |
Ending balance |  | 1,048 |  |  |
Consumer loans | Installment and other consumer |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 406 |  |  |  |
Provision (reversal) - CECL method | 11 |  |  |  |
(Charge-offs) | (1) |  |  |  |
Recoveries | 0 |  |  |  |
Ending balance | 291 | 406 | 291 |  |
Beginning balance | 406 | 284 | 284 | 310 | 378
Provision (reversal) - incurred loss method |  | 122 |  | (23) | (108)
(Charge-offs) |  | 0 |  | (3) | (2)
Recoveries |  | 0 |  | 0 | 42
Ending balance |  | 406 |  | 284 | 310
Consumer loans | Installment and other consumer | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | (125) |  |  |  |
Ending balance |  | (125) |  |  |
Consumer loans | Installment and other consumer | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 281 |  |  |  |
Ending balance |  | 281 |  |  |
Unallocated |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Provision (reversal) - CECL method | (451) |  |  |  |
(Charge-offs) | 0 |  |  |  |
Recoveries | 0 |  |  |  |
Ending balance | 1,300 |  | 1,300 |  |
Beginning balance | 1,265 | 653 | $ 653 | 494 | 718
Provision (reversal) - incurred loss method |  | 612 |  | 159 | (224)
(Charge-offs) |  | 0 |  | 0 | 0
Recoveries |  | 0 |  | 0 | 0
Ending balance |  | 1,265 |  | $ 653 | $ 494
Unallocated | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | 486 |  |  |  |
Ending balance |  | 486 |  |  |
Unallocated | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |  |
Beginning balance | $ 1,751 |  |  |  |
Ending balance |  | $ 1,751 |  |  |

X
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