Allowance for Credit Losses - Narrative (Details) $ in Millions	Mar. 31, 2023 USD ($)
Receivables [Abstract]
Outstanding balance of high risk loans, minimum	$ 0.5

Loan Balance For Reviewing High Risk Loans Minimum

No definition available.

Name:	cban_LoanBalanceForReviewingHighRiskLoansMinimum
Namespace Prefix:	cban_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant