Regulatory Matters - Additional Information (Detail) $ in Millions	Dec. 31, 2019 USD ($)
Banking and Thrift [Abstract]
Amount of capital available for payment of dividends	$ 629.1

Amount Of Capital Available For Payment Of Dividends

No definition available.

Name:	lbai_AmountOfCapitalAvailableForPaymentOfDividends
Namespace Prefix:	lbai_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant