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Consolidated Statements of Cash Flows (unaudited) (Parenthetical) $ in Millions | 9 Months Ended
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Sep. 30, 2022 USD ($)
Statement of Cash Flows [Abstract] |
Debt securities transfer, unrealized loss | $ 34.0

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- Definition Debt Securities, Available-for-Sale, Transfer To Held-to-maturity, Unrealized Gain (Loss) + References No definition available. + Details
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Namespace Prefix: | cban_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_StatementOfCashFlowsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration