XML 80 R69.htm IDEA: XBRL DOCUMENT v3.25.3

Note 7 - Deposits (Details Textual) - USD ($)	Sep. 30, 2025	Dec. 31, 2024
Deposit Liabilities, Money Market [Member]
Interest-Bearing Domestic Deposit, Brokered	$ 251,000	$ 279,000
Deposit Liabilities, Certificates of Deposits Less Than 100,000 [Member]
Interest-Bearing Domestic Deposit, Brokered	$ 369,400,000	$ 143,100,000

X

- Definition

Amount of interest-bearing domestic third-party deposits placed by or through the assistance of a deposit broker, also known as brokered deposit liabilities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(12))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

+ Details

Name:	us-gaap_InterestBearingDomesticDepositBrokered
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=fsbw_DepositLiabilitiesMoneyMarketMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=fsbw_DepositLiabilitiesCertificatesOfDepositsLessThan100000Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: