Loans, Troubled Debt Restructuring (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($) Bank_Loan	Sep. 30, 2017 USD ($) Bank_Loan	Sep. 30, 2018 USD ($) Bank_Loan	Sep. 30, 2017 USD ($) Bank_Loan
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, with No Related Allowance, Recorded Investment	$ 0	$ 0	$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts				2
Financing Receivable, Modifications, Number of Contracts \| Bank_Loan	1	0	1	2
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 199,000	$ 0	$ 199,000	$ 32,000
Financing Receivable, Modifications, Post-Modification Recorded Investment	199,000	0	199,000	23,000
Loan modifications classified as troubled debt restructurings [Abstract]
Troubled debt restructurings that subsequently defaulted within 12 months of the restructuring date			0	1,236,000
Financing Receivable, Modifications, with Related Allowance, Recorded Investment	$ 0	$ 23	$ 0	$ 23
Commercial and industrial [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Bank_Loan	0	0	0	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
Commercial, secured by real estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Bank_Loan	0	0	0	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 0
Residential real estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Bank_Loan	1	0	1	1
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 199,000	$ 0	$ 199,000	$ 18,000
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 199,000	$ 0	$ 199,000	$ 9,000
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Bank_Loan	0	0	0	1
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 14,000
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 0	$ 0	$ 14,000

Financing Receivable, Modifications, with No Related Allowance, Recorded Investment

No definition available.

Name:	lcnb_FinancingReceivableModificationswithNoRelatedAllowanceRecordedInvestment
Namespace Prefix:	lcnb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing Receivable, Modifications, with Related Allowance, Recorded Investment

+ References

No definition available.

+ Details

Name:	lcnb_FinancingReceivableModificationswithRelatedAllowanceRecordedInvestment
Namespace Prefix:	lcnb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	lcnb_LoanModificationsClassifiedAsTroubledDebtRestructuringsAbstract
Namespace Prefix:	lcnb_
Data Type:	xbrli:stringItemType
Balance Type:	na
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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

+ Details

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

- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

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

- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

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

- Definition

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Details

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

- Details

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

- Details

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