Allowance for Credit Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	$ 20,261	$ 33,719
Collectively evaluated	5,954,950	5,979,260
Acquired with deteriorated credit quality	937	8,253
Loans	5,976,148	6,021,232
Individually evaluated	4,251	1,355
Collectively evaluated	53,796	69,769
Total	58,047	71,124	$ 40,003
Non-owner occupied commercial
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	3,063	12,112
Collectively evaluated	2,313,047	2,382,717
Acquired with deteriorated credit quality	174	4,117
Loans	2,316,284	2,398,946
Individually evaluated	0	355
Collectively evaluated	20,071	25,555
Total	20,071	25,910	0
Owner occupied commercial
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	6,678	16,547
Collectively evaluated	901,638	809,935
Acquired with deteriorated credit quality	133	610
Loans	908,449	827,092
Individually evaluated	69	96
Collectively evaluated	3,895	3,859
Total	3,964	3,955	0
Mortgage-backed securities, multifamily
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	0	0
Collectively evaluated	972,233	813,225
Acquired with deteriorated credit quality	0	0
Loans	972,233	813,225
Individually evaluated	0	0
Collectively evaluated	8,309	7,253
Total	8,309	7,253
Non-owner occupied residential
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	2,567	1,459
Collectively evaluated	174,463	198,334
Acquired with deteriorated credit quality	67	436
Loans	177,097	200,229
Individually evaluated	0	43
Collectively evaluated	2,380	3,278
Total	2,380	3,321	0
Commercial, industrial and other
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	6,537	1,596
Collectively evaluated	455,306	715,129
Acquired with deteriorated credit quality	563	1,464
Loans	462,406	718,189
Individually evaluated	4,182	830	5
Collectively evaluated	5,709	12,835
Total	9,891	13,665	3,289
Construction
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	0	515
Collectively evaluated	302,228	265,649
Acquired with deteriorated credit quality	0	719
Loans	302,228	266,883
Individually evaluated	0	0	0
Collectively evaluated	838	786
Total	838	786	2,672
Equipment finance
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	0	0
Collectively evaluated	123,212	116,690
Acquired with deteriorated credit quality	0	0
Loans	123,212	116,690
Individually evaluated	0	0	10
Collectively evaluated	3,663	6,552
Total	3,663	6,552	957
Residential mortgage
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	1,416	1,490
Collectively evaluated	437,294	375,482
Acquired with deteriorated credit quality	0	408
Loans	438,710	377,380
Individually evaluated	0	0	104
Collectively evaluated	3,914	3,623
Total	3,914	3,623	1,725
Consumer
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	0	0
Collectively evaluated	275,529	302,099
Acquired with deteriorated credit quality	0	499
Loans	275,529	302,598
Individually evaluated	0	31	5
Collectively evaluated	5,017	6,028
Total	$ 5,017	$ 6,059	$ 2,410

Debt Securities, Allowance for Credit Loss

No definition available.

Name:	lbai_DebtSecuritiesAllowanceForCreditLossLineItems
Namespace Prefix:	lbai_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable, Acquired With Credit Deterioration

+ References

No definition available.

+ Details

Name:	lbai_FinancingReceivableAcquiredWithCreditDeterioration
Namespace Prefix:	lbai_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
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=123577603&loc=SL6953423-111524

+ 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

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=123577603&loc=SL6953423-111524

+ Details

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

- Definition

Amount excluding accrued interest, before allowance for credit loss, of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 3B
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss
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=123577603&loc=SL6953423-111524

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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