XML 100 R89.htm IDEA: XBRL DOCUMENT v3.25.1

Note 13 - Business Segments (Details Textual)	Mar. 31, 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