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Related Party Transactions (Narrative) (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
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Principal Officers and Directors and Their Affiliates [Member] |  |
Related Party Transaction [Line Items] |  |
Total deposits | $ 7,604 | $ 5,137
Affiliated Entity [Member] | Isabella Bank Foundation [Member] |  |
Related Party Transaction [Line Items] |  |
Common Stock, Shares Held by Related Party | 44,350 | 44,350

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- Definition Common Stock, Shares Held by Related Party + References No definition available. + Details
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Balance Type: | na
Period Type: | instant

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- Definition Amount of deposits held by the entity for a related party (entity, shareholder, employee). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(k)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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Balance Type: | credit
Period Type: | instant

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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- Details
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- Details
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Namespace Prefix: |
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