Loans and Allowance for Credit Losses on Loans (Troubled Debt Restructuring by Portfolio Segment) (Details)	12 Months Ended
Dec. 31, 2022 USD ($) loan	Dec. 31, 2021 USD ($) loan	Dec. 31, 2020 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	3	0
Pre-Modification Outstanding Recorded Investment	$ 69,000	$ 346,000	$ 0
Post-Modification Outstanding Recorded Investment	96,000	357,000	0
Specific Reserve	$ 0	$ 6,000	$ 0
Home equity \| Interest Rate Concession and Payment Deferral
Financing Receivable, Modifications [Line Items]
Number of Contracts \| loan	0	1	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 159,000	$ 0
Post-Modification Outstanding Recorded Investment	0	170,000	0
Specific Reserve	$ 0	$ 0	$ 0
Home equity \| Extended Maturity
Financing Receivable, Modifications [Line Items]
Number of Contracts \| loan	1	2	0
Pre-Modification Outstanding Recorded Investment	$ 69,000	$ 187,000	$ 0
Post-Modification Outstanding Recorded Investment	96,000	187,000	0
Specific Reserve	$ 0	$ 6,000	$ 0

Allowance Related to Troubled Debt Restructurings assigned during period

No definition available.

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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

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Namespace Prefix:	us-gaap_
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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 https://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

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

+ References

+ Details

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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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