XML 49 R38.htm IDEA: XBRL DOCUMENT v3.25.3

Note 1 - Basis of Presentation and Summary of Significant Accounting Policies (Details Textual)	Sep. 30, 2025
Number of Bank Branches	27

X

- Definition

Represents the number bank branches.

+ References

No definition available.

+ Details

Name:	fsbw_NumberOfBankBranches
Namespace Prefix:	fsbw_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant