Loans and Other Real Estate - Summary of Restructured Loans (Detail) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($) Contract	Sep. 30, 2018 USD ($) Contract	Sep. 30, 2019 USD ($) Contract	Sep. 30, 2018 USD ($) Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts \| Contract	2	1	2	5
Pre- Modification Outstanding Recorded Investment	$ 83	$ 1,175	$ 83	$ 3,952
Post- Modification Outstanding Recorded Investment	$ 83	$ 1,175	$ 83	$ 3,952
Commercial, secured by real estate
Financing Receivable, Modifications [Line Items]
Number of Contracts \| Contract	0	1	0	4
Pre- Modification Outstanding Recorded Investment	$ 0	$ 1,175	$ 0	$ 3,002
Post- Modification Outstanding Recorded Investment	$ 0	$ 1,175	$ 0	$ 3,002
Commercial, industrial and other
Financing Receivable, Modifications [Line Items]
Number of Contracts \| Contract			0	1
Pre- Modification Outstanding Recorded Investment			$ 0	$ 950
Post- Modification Outstanding Recorded Investment			$ 0	$ 950
Home Equity And Consumer
Financing Receivable, Modifications [Line Items]
Number of Contracts \| Contract	2	0
Pre- Modification Outstanding Recorded Investment	$ 83	$ 0
Post- Modification Outstanding Recorded Investment	$ 83	$ 0

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.

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

- Details

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

- Details

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

- Details

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