LOANS AND ALLOWANCE FOR CREDIT LOSSES ON LOANS (Troubled Debt Restructuring by Portfolio Segment) (Details) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2022 USD ($) loan	Jun. 30, 2021 USD ($) loan	Jun. 30, 2022 USD ($) loan	Jun. 30, 2021 USD ($) loan
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| loan	0	1	0	2
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 0	$ 144	$ 0	$ 303
Financing Receivable, Troubled Debt Restructuring, Postmodification	0	143	0	313
Allowance Related to Troubled Debt Restructurings assigned during period	$ 0	$ 6	$ 0	$ 62
Home equity \| Interest Rate Concession and Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| loan			0	1
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 0	$ 159
Financing Receivable, Troubled Debt Restructuring, Postmodification			0	170
Allowance Related to Troubled Debt Restructurings assigned during period			$ 0	$ 56
Home equity \| Extended Maturity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| loan	0	1	0	1
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 0	$ 144	$ 0	$ 144
Financing Receivable, Troubled Debt Restructuring, Postmodification	0	143	0	143
Allowance Related to Troubled Debt Restructurings assigned during period	$ 0	$ 6	$ 0	$ 6

Allowance Related to Troubled Debt Restructurings assigned during period

No definition available.

Name:	cac_AllowanceRelatedToTroubledDebtRestructuringsAssignedDuringPeriod
Namespace Prefix:	cac_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, before troubled debt restructuring, of financing receivable to be modified.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=cac_HomeEquityPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=cac_InterestRateConcessionAndPaymentDeferralMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: