Name:	cban_BankOwnedLifeInsuranceAbstract
Namespace Prefix:	cban_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Discounted percentage to account for selling and marketing costs.

+ References

No definition available.

+ Details

Name:	cban_DiscountedPercentageForSellingAndMarketingCost
Namespace Prefix:	cban_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of loan portfolio concentrated in loans secured by real estate.

+ References

No definition available.

+ Details

Name:	cban_PercentageOfLoanPortfolioConcentratedInLoansSecuredByRealEstate
Namespace Prefix:	cban_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum probability of uncertain tax positions of being realized upon settlement.

+ References

No definition available.

+ Details

Name:	cban_ProbabilityOfUncertainTaxPositionsOfBeingRealizedUponSettlementMinimum
Namespace Prefix:	cban_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_AccountingPoliciesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.17)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 4

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6812-107765

+ Details

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

- Details

Name:	us-gaap_IncomeTaxUncertaintiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the methodology for computing depreciation for classes of depreciable assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentDepreciationMethods
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Summary of Significant Accounting Policies [Abstract]
Percentage of loan portfolio concentrated in loans secured by real estate (in hundredths)	87.00%
Discounted percentage for selling and marketing cost (in hundredths)	10.00%
Income Taxes [Abstract]
Probability of uncertain tax positions of being realized upon settlement, minimum (in hundredths)	50.00%
Bank-Owned Life Insurance [Abstract]
Cash surrender value of insurance contracts	$ 14,371	$ 13,940
Banking Premises [Member]
Premises and equipment [Line Items]
Methods	Straight-Line and Accelerated
Banking Premises [Member] \| Minimum [Member]
Premises and equipment [Line Items]
Useful lives of the assets	15 years
Banking Premises [Member] \| Maximum [Member]
Premises and equipment [Line Items]
Useful lives of the assets	40 years
Furniture and Equipment [Member]
Premises and equipment [Line Items]
Methods	Straight-Line and Accelerated
Furniture and Equipment [Member] \| Minimum [Member]
Premises and equipment [Line Items]
Useful lives of the assets	5 years
Furniture and Equipment [Member] \| Maximum [Member]
Premises and equipment [Line Items]
Useful lives of the assets	10 years