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Basis of Accounting and Consolidation - Schedule of Impact of ASU 2016-13 Adoption of PCD Assets Previously Classified as PCI (Details) - USD ($) | Sep. 30, 2021 | Jun. 30, 2021 | Dec. 31, 2020 | Sep. 30, 2020 | Jun. 30, 2020 | Jan. 01, 2020 | Dec. 31, 2019
--- | --- | --- | --- | --- | --- | --- | ---
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans | $ 53,983,000 | $ 54,597,000 | $ 41,910,000 | $ 41,915,000 | $ 38,381,000 |  | $ 26,911,000
Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 26,911,000
ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | $ 28,583,000 |
ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 1,672,000 |
Construction and Land Development | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 1,146,000
Construction and Land Development | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 1,033,000 |
Construction and Land Development | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | (113,000) |
1-4 Family Residential Properties | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 1,386,000
1-4 Family Residential Properties | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 2,142,000 |
1-4 Family Residential Properties | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 756,000 |
Commercial Real Estate | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 11,198,000
Commercial Real Estate | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 11,739,000 |
Commercial Real Estate | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 541,000 |
Commercial & Industrial | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 9,273,000
Commercial & Industrial | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 9,428,000 |
Commercial & Industrial | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 155,000 |
Financial Asset Acquired with Credit Deterioration | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 365,000
Financial Asset Acquired with Credit Deterioration | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 1,198,000 |
Financial Asset Acquired with Credit Deterioration | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 833,000 |
Financial Asset Acquired with Credit Deterioration | Construction and Land Development | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 0
Financial Asset Acquired with Credit Deterioration | Construction and Land Development | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 291,000 |
Financial Asset Acquired with Credit Deterioration | Construction and Land Development | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 291,000 |
Financial Asset Acquired with Credit Deterioration | 1-4 Family Residential Properties | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 6,000
Financial Asset Acquired with Credit Deterioration | 1-4 Family Residential Properties | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 48,000 |
Financial Asset Acquired with Credit Deterioration | 1-4 Family Residential Properties | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 42,000 |
Financial Asset Acquired with Credit Deterioration | Commercial Real Estate | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | 359,000
Financial Asset Acquired with Credit Deterioration | Commercial Real Estate | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 818,000 |
Financial Asset Acquired with Credit Deterioration | Commercial Real Estate | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 459,000 |
Financial Asset Acquired with Credit Deterioration | Commercial & Industrial | Pre-ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  |  | $ 0
Financial Asset Acquired with Credit Deterioration | Commercial & Industrial | ASU 2016-13 |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | 41,000 |
Financial Asset Acquired with Credit Deterioration | Commercial & Industrial | ASU 2016-13 | Impact of ASU |  |  |  |  |  |  |
New Accounting Pronouncements Or Change In Accounting Principle [Line Items] |  |  |  |  |  |  |
Allowance for credit losses on loans |  |  |  |  |  | $ 41,000 |

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