Name:	cban_OtherRealEstateAcquired
Namespace Prefix:	cban_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Gain (loss) on sale of other real estate excluding physical possession.

No definition available.

Name:	cban_OtherRealEstateGainLossOnSaleAndWriteDowns
Namespace Prefix:	cban_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Transfers of other real estate to bank premises.

No definition available.

Name:	cban_OtherRealEstateTransfers
Namespace Prefix:	cban_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(4))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Name:	us-gaap_OtherRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Additions of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure.

No definition available.

Name:	us-gaap_OtherRealEstateAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Disposals of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure.

No definition available.

Name:	us-gaap_OtherRealEstateDisposals
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.