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Merger - Narrative (Details) - USD ($) $ in Thousands |  |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | --- | ---
Sep. 30, 2021 | Aug. 06, 2021 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Business Combination, Separately Recognized Transactions [Line Items] |  |  |  |  |  |  |
Goodwill | $ 72,754 |  | $ 72,754 |  | $ 72,754 |  | $ 30,140
Core deposit intangible | 6,998 |  | 6,998 |  | 6,998 |  | $ 3,831
Amortization of core deposit intangible |  |  | $ 334 | $ 213 | $ 742 | $ 639 |
American River Bank (ARB) Merger |  |  |  |  |  |  |
Business Combination, Separately Recognized Transactions [Line Items] |  |  |  |  |  |  |
Goodwill |  | $ 42,614 |  |  |  |  |
American River Bank (ARB) Merger | Core deposit intangible amortization |  |  |  |  |  |  |
Business Combination, Separately Recognized Transactions [Line Items] |  |  |  |  |  |  |
Core deposit intangible |  | $ 3,900 |  |  |  |  |
Amortization of core deposit intangible | $ 129 |  |  |  |  |  |
American River Bank (ARB) Merger | Bank of Marin |  |  |  |  |  |  |
Business Combination, Separately Recognized Transactions [Line Items] |  |  |  |  |  |  |
Merger agreement, shares exchange ratio (in shares) |  | 0.575 |  |  |  |  |
Business combination, number of common stock issued (in shares) |  | 3,441,235 |  |  |  |  |

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- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 + Details
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- Definition Bank deposits belonging to an acquired bank that can be counted on as a stable source of lending funds. These deposits have the following attributes: predictable costs and low sensitivity to interest rates. This intangible asset is usually amortized over its estimated useful life. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
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