Allowance for Loan Losses - Impaired Financing Receivables Excluding PCI Loans - Recorded Investment and Unpaid Principal Balances (Detail) $ in Thousands	Dec. 31, 2022 USD ($)
Financing Receivable, Impaired [Line Items]
Impaired financing receivables, with no related allowance recorded, Recorded Investment	$ 467
Impaired financing receivables, with no related allowance recorded, Unpaid Principal Balance	492
Impaired financing receivables, with an allowance recorded, Recorded Investment	157
Impaired financing receivables, with an allowance recorded, Unpaid Principal Balance	161
Impaired financing receivables, with an allowance recorded, Related Allowance	7
Impaired financing receivables, Recorded Investment, Total	624
Impaired financing receivables, Unpaid Principal Balance, Total	653
Impaired financing receivables, Related Allowance, Total	7
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired financing receivables, with no related allowance recorded, Recorded Investment	82
Impaired financing receivables, with no related allowance recorded, Unpaid Principal Balance	82
Impaired financing receivables, with an allowance recorded, Recorded Investment	150
Impaired financing receivables, with an allowance recorded, Unpaid Principal Balance	150
Impaired financing receivables, with an allowance recorded, Related Allowance	6
Impaired financing receivables, Recorded Investment, Total	232
Impaired financing receivables, Unpaid Principal Balance, Total	232
Impaired financing receivables, Related Allowance, Total	6
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired financing receivables, with no related allowance recorded, Recorded Investment	385
Impaired financing receivables, with no related allowance recorded, Unpaid Principal Balance	410
Impaired financing receivables, with an allowance recorded, Recorded Investment	7
Impaired financing receivables, with an allowance recorded, Unpaid Principal Balance	11
Impaired financing receivables, with an allowance recorded, Related Allowance	1
Impaired financing receivables, Recorded Investment, Total	392
Impaired financing receivables, Unpaid Principal Balance, Total	421
Impaired financing receivables, Related Allowance, Total	$ 1

Impaired financing receivable with and no related allowance.

No definition available.

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Namespace Prefix:	civb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-14A

+ Details

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

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-15

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-15

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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- Details

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Namespace Prefix:
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- Details

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