ALLOWANCE FOR LOAN LOSSES AND CREDIT QUALITY - Balance In The Allowance For Loan Losses And The Recorded Investment In Loans By Portfolio Management (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Ending allowance balance attributable to loans:
Individually evaluated for impairment	$ 8,041	$ 10,384
Collectively evaluated for impairment	53,367	40,268
Total ending allowance balance	61,408	50,652	$ 48,453	$ 47,121
Loans:
Loans individually evaluated for impairment	20,179	27,829
Loans collectively evaluated for impairment	4,628,977	4,037,999
Total ending loans balance	4,649,156	4,065,828
Commercial and Industrial Loans [Member]
Ending allowance balance attributable to loans:
Individually evaluated for impairment	6,310	9,324
Collectively evaluated for impairment	22,023	16,465
Total ending allowance balance	28,333	25,789	22,518	21,097
Loans:
Loans individually evaluated for impairment	12,533	19,580
Loans collectively evaluated for impairment	1,772,393	1,407,246
Total ending loans balance	1,784,926	1,426,826
Commercial Real Estate and Multi-family Residential Loans
Ending allowance balance attributable to loans:
Individually evaluated for impairment	1,377	538
Collectively evaluated for impairment	21,530	15,258
Total ending allowance balance	22,907	15,796	15,393	14,714
Loans:
Loans individually evaluated for impairment	5,518	4,998
Loans collectively evaluated for impairment	1,887,054	1,665,842
Total ending loans balance	1,892,572	1,670,840
Agri-business and Agricultural Loans [Member]
Ending allowance balance attributable to loans:
Individually evaluated for impairment	84	90
Collectively evaluated for impairment	2,959	3,779
Total ending allowance balance	3,043	3,869	4,305	4,920
Loans:
Loans individually evaluated for impairment	428	445
Loans collectively evaluated for impairment	429,234	379,186
Total ending loans balance	429,662	379,631
Other Commercial
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	416	447
Total ending allowance balance	416	447	368	577
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	93,912	112,166
Total ending loans balance	93,912	112,166
Consumer 1-4 Family Mortgage Loans [Member]
Ending allowance balance attributable to loans:
Individually evaluated for impairment	270	426
Collectively evaluated for impairment	2,349	1,660
Total ending allowance balance	2,619	2,086	2,292	2,768
Loans:
Loans individually evaluated for impairment	1,700	2,789
Loans collectively evaluated for impairment	342,999	375,210
Total ending loans balance	344,699	377,999
Other Consumer
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	6
Collectively evaluated for impairment	951	339
Total ending allowance balance	951	345	283	379
Loans:
Loans individually evaluated for impairment	0	17
Loans collectively evaluated for impairment	103,385	98,349
Total ending loans balance	103,385	98,366
Unallocated
Ending allowance balance attributable to loans:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	3,139	2,320
Total ending allowance balance	3,139	2,320	$ 3,294	$ 2,666
Loans:
Loans individually evaluated for impairment	0	0
Loans collectively evaluated for impairment	0	0
Total ending loans balance	$ 0	$ 0

No definition available.

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

- Definition

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

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
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

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
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

+ 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

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for 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 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544

Reference 3: 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=121611835&loc=SL6953423-111524

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

+ Details

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

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. 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=121593590&loc=d3e4428-111522

Reference 2: 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=121611835&loc=d3e5074-111524

+ Details

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

- 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_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:

- Details

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