XML 99 R88.htm IDEA: XBRL DOCUMENT v3.25.2

Note 13 - Business Segments (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)
Number of Bank Branches	27		27
Noninterest Expense	$ 25,502	$ 23,857	$ 50,556	$ 47,386
Home Lending [Member] | Allocated Overhead Expense [Member]
Noninterest Expense	$ 1,800	$ 1,500	$ 3,700	$ 3,000

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

X

- Definition

Total aggregate amount of all noninterest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476153/220-40-55-21

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(14))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

Name:	us-gaap_NoninterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=fsbw_HomeLendingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_NatureOfExpenseAxis=fsbw_AllocatedOverheadExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: