Impairment or observable price adjustments of investments.

No definition available.

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Namespace Prefix:	lsbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Potential limited partnership investment commitment.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-11

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-10

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482454/460-10-45-1

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Net cash outflow or inflow from limited partnership investments held by the entity for investment purposes.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=us-gaap_UnusedLinesOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=lsbk_CommitmentToFundLimitedPartnershipInvestmentMember
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Commitments to Extend Credit and Other Obligations (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2026	Apr. 01, 2026	Dec. 31, 2025
Other Commitments [Line Items]
Off-balance sheet allowance for credit loss	$ 495,000	$ 495,000		$ 361,000
Castle Creek Launchpad Fund II (SBIC) LP [Member]
Other Commitments [Line Items]
Potential limited partnership investment commitment	1,800,000	1,800,000
Funded for limited partnership investment		248,000
Impairment or observable price adjustments of investments	0	0
Castle Creek Launchpad Fund II (SBIC) LP [Member] \| Maximum [Member]
Other Commitments [Line Items]
Potential limited partnership investment commitment			$ 2,000,000
Commitments to Grant Loans [Member]
Other Commitments [Line Items]
Commitments to extend credit and other obligations	23,924,000	23,924,000		17,644,000
Unfunded Commitments to Fund Loans and Lines of Credit [Member]
Other Commitments [Line Items]
Commitments to extend credit and other obligations	103,939,000	103,939,000		92,748,000
Commercial and Standby Letters of Credit [Member]
Other Commitments [Line Items]
Commitments to extend credit and other obligations	93,000	93,000		720,000
Commitment to Fund Limited Partnership Investment [Member]
Other Commitments [Line Items]
Commitments to extend credit and other obligations	$ 1,752,000	$ 1,752,000		$ 0