Increase (decrease) in allowance for loan loss.

No definition available.

Name:	lkfn_IncreaseDecreaseInAllowanceForLoanLoss
Namespace Prefix:	lkfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The minimum loan amount required for credit quality analysis.

+ References

No definition available.

+ Details

Name:	lkfn_LoanAmountOfCreditQualityAnalysis
Namespace Prefix:	lkfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount included in the allowance for loan loss for specific reserves on loans whose terms have been modified in trouble debt restructuring.

+ References

No definition available.

+ Details

Name:	lkfn_LoansModifiedInTroubledDebtRestructuredLoans
Namespace Prefix:	lkfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	lkfn_TroubledDebtRestructuringAbstract
Namespace Prefix:	lkfn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of financing receivable modified as troubled debt restructuring.

+ 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=118936363&loc=SL6953676-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18845-111554

+ Details

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

- Definition

Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953682-111524

+ Details

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

- Details

Name:	us-gaap_CollateralAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=lkfn_TotalCommercialAndIndustrialLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	lkfn_PortfolioSegmentAxis=lkfn_NonWorkingCapitalLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

ALLOWANCE FOR LOAN LOSSES AND CREDIT QUALITY - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Troubled Debt Restructuring [Abstract]
Loans Modified In Troubled Debt Restructured Loans	$ 2,500,000	$ 3,700,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	601,000	0	$ 0
Loan amount of credit quality analysis	250,000
Construction and land development loans
Troubled Debt Restructuring [Abstract]
Financing Receivable, Modifications, Recorded Investment	2,400,000	1,400,000
Commercial and Industrial Loans
Troubled Debt Restructuring [Abstract]
Increase (decrease) in allowance for loan loss			513,000
Financing Receivable, Modifications, Recorded Investment			1,900,000
Commercial and Industrial Loans \| Non-working capital loans
Troubled Debt Restructuring [Abstract]
Financing Receivable, Modifications, Recorded Investment			2,500,000
Commercial Real Estate and Multi-family Residential Loans
Troubled Debt Restructuring [Abstract]
Increase (decrease) in allowance for loan loss			$ 27,000
Financing Receivable, Modifications, Recorded Investment	1,900,000	1,300,000
Consumer 1-4 Family Mortgage Loans
Troubled Debt Restructuring [Abstract]
Increase (decrease) in allowance for loan loss	$ 484,000	189,000
Financing Receivable, Modifications, Recorded Investment		$ 593,000