Financing receivable acquired with credit deterioration.

No definition available.

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Namespace Prefix:	civb_
Data Type:	xbrli:monetaryItemType
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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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- Definition

For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	credit
Period Type:	instant

- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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

- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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

- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

+ Details

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

- Details

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- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=civb_CommercialAndAgricultureMember
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Data Type:	na
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Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=civb_CommercialRealEstateOwnerOccupiedMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=civb_CommercialRealEstateNonOwnerOccupiedMember
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Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=civb_RealEstateConstructionMember
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- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=civb_FarmRealEstateMember
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- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=civb_ConsumerAndOtherMember
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Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_UnallocatedFinancingReceivablesMember
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Allowance for Loan Losses - Ending Allocation of Allowance for Loan Losses and Loan Balances Outstanding (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Individually evaluated for impairment	$ 119		$ 125
Allowance for loan losses, Collectively evaluated for impairment	12,719		12,883
Allowance for loan losses, Total	12,867	$ 12,814	13,134	$ 13,047	$ 13,300	$ 13,305
Outstanding loan balances, Individually evaluated for impairment	3,602		3,460
Outstanding loan balances, Collectively evaluated for impairment	1,176,261		1,160,986
Outstanding loan balances, Total	1,180,032		1,164,661
Receivables Acquired with Deteriorated Credit Quality [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans acquired with credit deterioration	29		126
Loan balance of loans acquired with credit deterioration	169		215
Commercial and Agriculture [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Individually evaluated for impairment	5		4
Allowance for loan losses, Collectively evaluated for impairment	1,625		1,476
Allowance for loan losses, Total	1,630	1,359	1,562	1,608	1,569	2,018
Outstanding loan balances, Individually evaluated for impairment	961		438
Outstanding loan balances, Collectively evaluated for impairment	152,720		151,948
Outstanding loan balances, Total	153,742		152,473
Commercial and Agriculture [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans acquired with credit deterioration			82
Loan balance of loans acquired with credit deterioration	61		87
Commercial Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Individually evaluated for impairment	8		6
Allowance for loan losses, Collectively evaluated for impairment	2,153		2,037
Allowance for loan losses, Total	2,161	2,030	2,043	2,010	2,259	2,171
Outstanding loan balances, Individually evaluated for impairment	517		1,010
Outstanding loan balances, Collectively evaluated for impairment	169,228		163,089
Outstanding loan balances, Total	169,745		164,099
Commercial Real Estate Non Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	5,135		5,307
Allowance for loan losses, Total	5,135	5,670	5,307	4,739	4,543	4,606
Outstanding loan balances, Individually evaluated for impairment	39		44
Outstanding loan balances, Collectively evaluated for impairment	431,056		425,579
Outstanding loan balances, Total	431,095		425,623
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Individually evaluated for impairment	100		109
Allowance for loan losses, Collectively evaluated for impairment	1,562		1,757
Allowance for loan losses, Total	1,691	1,750	1,910	2,676	3,022	3,089
Outstanding loan balances, Individually evaluated for impairment	1,307		1,360
Outstanding loan balances, Collectively evaluated for impairment	269,792		267,247
Outstanding loan balances, Total	271,207		268,735
Residential Real Estate [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans acquired with credit deterioration	29		44
Loan balance of loans acquired with credit deterioration	108		128
Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	861		834
Allowance for loan losses, Total	861	820	834	482	413	420
Outstanding loan balances, Collectively evaluated for impairment	100,812		97,531
Outstanding loan balances, Total	100,812		97,531
Farm Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Individually evaluated for impairment	6		6
Allowance for loan losses, Collectively evaluated for impairment	404		424
Allowance for loan losses, Total	410	411	430	425	407	442
Outstanding loan balances, Individually evaluated for impairment	778		608
Outstanding loan balances, Collectively evaluated for impairment	37,067		38,853
Outstanding loan balances, Total	37,845		39,461
Consumer and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	300		290
Allowance for loan losses, Total	300	247	290	324	354	314
Outstanding loan balances, Collectively evaluated for impairment	15,586		16,739
Outstanding loan balances, Total	15,586		16,739
Unallocated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	679		758
Allowance for loan losses, Total	$ 679	$ 527	$ 758	$ 783	$ 733	$ 245