Schedule of Gains and Losses from Changes in Fair Value of Loans Held for Sale (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Total change in fair value	$ (279)	$ (315)	$ (506)	$ 1,657

The amount of interest and fee income earned from loans held-for-sale, including mortgage loans, and interest earned from direct financing and sales-type leases held-for-sale.

No definition available.

Name:	LARK_InterestAndFeeIncomeLoansAndLeaseHeldForSale
Namespace Prefix:	LARK_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration