ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ 71,215	$ 67,526	$ 72,606	$ 67,773
Provision for credit losses	800	0	5,150	417
Loans charged-off	(390)	(98)	(6,286)	(838)
Recoveries	433	95	588	171
Net loans (charged-off) recovered	43	(3)	(5,698)	(667)
Ending balance	72,058	67,523	72,058	67,523
Unallocated
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	840	482	554	450
Provision for credit losses	(489)	165	(203)	197
Loans charged-off	0	0	0	0
Recoveries	0	0	0	0
Net loans (charged-off) recovered	0	0	0	0
Ending balance	351	647	351	647
Commercial Portfolio Segment \| Commercial and Industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	31,190	31,322	35,290	30,595
Provision for credit losses	(272)	(139)	1,232	591
Loans charged-off	(7)	(13)	(5,651)	(32)
Recoveries	67	25	107	41
Net loans (charged-off) recovered	60	12	(5,544)	9
Ending balance	30,978	31,195	30,978	31,195
Commercial Portfolio Segment \| Commercial Real Estate and Multifamily Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	29,036	26,257	27,394	26,535
Provision for credit losses	1,593	191	3,235	510
Loans charged-off	0	0	0	(597)
Recoveries	284	0	284	0
Net loans (charged-off) recovered	284	0	284	(597)
Ending balance	30,913	26,448	30,913	26,448
Commercial Portfolio Segment \| Agri-business and Agricultural
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	4,621	4,761	4,429	5,034
Provision for credit losses	(219)	(8)	(27)	(281)
Loans charged-off	0	0	0	0
Recoveries	0	0	0	0
Net loans (charged-off) recovered	0	0	0	0
Ending balance	4,402	4,753	4,402	4,753
Commercial Portfolio Segment \| Other Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	1,034	1,058	917	1,146
Provision for credit losses	86	(345)	203	(433)
Loans charged-off	0	0	0	0
Recoveries	0	0	0	0
Net loans (charged-off) recovered	0	0	0	0
Ending balance	1,120	713	1,120	713
Consumer Portfolio Segment \| Consumer 1-4 Family Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	3,398	2,606	3,001	2,866
Provision for credit losses	51	34	445	(214)
Loans charged-off	(14)	0	(14)	(22)
Recoveries	13	34	16	44
Net loans (charged-off) recovered	(1)	34	2	22
Ending balance	3,448	2,674	3,448	2,674
Consumer Portfolio Segment \| Other Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	1,096	1,040	1,021	1,147
Provision for credit losses	50	102	265	47
Loans charged-off	(369)	(85)	(621)	(187)
Recoveries	69	36	181	86
Net loans (charged-off) recovered	(300)	(49)	(440)	(101)
Ending balance	$ 846	$ 1,093	$ 846	$ 1,093

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-1

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix:	us-gaap_
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

+ Details

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

- Definition

Amount, excluding accrued interest, of decrease (increase) in allowance for credit loss on financing receivable from writeoff (recovery). Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=lkfn_OtherCommercialMember
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:

- Details

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

- Details

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