Fair Value of Financial Instruments and Fair Value Measurements (Details 3) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
One-to-four family residential real estate [Member]
Impaired Loans Fair Value Disclosure	$ 266	$ 1,135
Fair Value Measurements, Valuation Techniques	Sales comparison	Sales comparison
Fair Value Measurements, Changes in Valuation Techniques	Adjustment to appraised value	Adjustment to appraised value
One-to-four family residential real estate [Member] \| Minimum [Member]
Fair Value Measurements Sales Comparison Range	0.00%	10.00%
One-to-four family residential real estate [Member] \| Maximum [Member]
Fair Value Measurements Sales Comparison Range	40.00%	47.00%
Commercial loans [Member]
Impaired Loans Fair Value Disclosure		$ 206
Fair Value Measurements, Valuation Techniques		Sales comparison
Fair Value Measurements, Changes in Valuation Techniques		Adjustment to comparable sales
Commercial loans [Member] \| Minimum [Member]
Fair Value Measurements Sales Comparison Range		15.00%
Commercial loans [Member] \| Maximum [Member]
Fair Value Measurements Sales Comparison Range		60.00%
Agriculture loans [Member]
Impaired Loans Fair Value Disclosure		$ 134
Fair Value Measurements, Valuation Techniques		Sales comparison
Fair Value Measurements, Changes in Valuation Techniques		Adjustment to appraised value
Fair Value Measurements Sales Comparison Range		60.00%
Consumer loans [Member]
Impaired Loans Fair Value Disclosure	$ 16	$ 30
Fair Value Measurements, Valuation Techniques	Sales comparison	Sales comparison
Fair Value Measurements, Changes in Valuation Techniques	Adjustment to comparable sales	Adjustment to comparable sales
Fair Value Measurements Sales Comparison Range	0.00%	20.00%
One-to-four family residential real estate [Member]
Real Estate Owned Fair Value Disclosure		$ 37
Fair Value Measurements, Valuation Techniques		Sales comparison
Fair Value Measurements, Changes in Valuation Techniques		Adjustment to appraised value
Fair Value Measurements Sales Comparison Range		10.00%
Commercial real estate [Member]
Impaired Loans Fair Value Disclosure		$ 30
Real Estate Owned Fair Value Disclosure		$ 45
Fair Value Measurements, Valuation Techniques		Sales comparison
Fair Value Measurements, Changes in Valuation Techniques		Adjustment to appraised value
Fair Value Measurements Sales Comparison Range		28.00%
Commercial real estate [Member] \| One-to-four family residential real estate [Member]
Real Estate Owned Fair Value Disclosure		$ 45
Fair Value Measurements, Valuation Techniques		Sales comparison
Fair Value Measurements, Changes in Valuation Techniques		Adjustment to appraised value
Fair Value Measurements Sales Comparison Range		10.00%

The range of Level 3 fair value measurements for impaired loans measured at fair value on a non-recurring basis.

No definition available.

Name:	lark_FairValueMeasurementsSalesComparisonRange
Namespace Prefix:	lark_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as impaired loans disclosure.

+ References

No definition available.

+ Details

Name:	lark_ImpairedLoansFairValueDisclosure
Namespace Prefix:	lark_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of real estate owned fair value disclosure.

+ References

No definition available.

+ Details

Name:	lark_RealEstateOwnedFairValueDisclosure
Namespace Prefix:	lark_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Description of the changes in valuation technique(s) and related inputs used to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementsChangesInValuationTechniques
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the inputs and valuation technique(s) used to measure fair value.

+ References

+ Details

Name:	us-gaap_FairValueMeasurementsValuationTechniques
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAxis=lark_OnetofourFamilyResidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAxis=lark_AgricultureLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAxis=us-gaap_ResidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: