Comprehensive Income - Narrative (Details) $ in Thousands	3 Months Ended
Sep. 30, 2018 USD ($)
Equity [Abstract]
Residual tax effect in AOCI	$ 693

Other Comprehensive Income (Loss), Available-for-sale Securities, Derivatives, and Pensions, Revaluation, Tax

No definition available.

Name:	lbai_OtherComprehensiveIncomeLossAvailableforsaleSecuritiesDerivativesandPensionsRevaluationTax
Namespace Prefix:	lbai_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration