Regulatory Capital Requirements - Schedule of Compliance with Regulatory Capital Requirements for Mortgage Companies (Details) (Parenthetical)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Company's Regulatory Capital Requirements [Member]
Tier one capital conversation buffer	2.50%	1.875%

The percentage of capital buffer to be maintained other than minimum capital requirements.

No definition available.

Name:	LARK_TierOneCapitalConversationBuffer
Namespace Prefix:	LARK_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration