Allowance for Credit Losses - Narrative (Details) $ in Thousands	6 Months Ended
Jun. 30, 2025 USD ($)
Receivables [Abstract]
Supportable forecast period (in years)	1 year
Outstanding balance of high risk loans, minimum	$ 500

Financing Receivable, Allowance for Credit Loss, Forecast Period

No definition available.

Name:	cban_FinancingReceivableAllowanceForCreditLossForecastPeriod
Namespace Prefix:	cban_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration