v3.25.2
Document And Entity Information
Jul. 22, 2025
Document Information [Line Items]  
Entity, Registrant Name FS BANCORP, INC.
Document, Type 8-K
Document, Period End Date Jul. 22, 2025
Entity, Incorporation, State or Country Code WA
Entity, File Number 001-35589
Entity, Tax Identification Number 45-4585178
Entity, Address, Address Line One 6920 220th Street SW
Entity, Address, City or Town Mountlake Terrace
Entity, Address, State or Province WA
Entity, Address, Postal Zip Code ​98043
City Area Code 425
Local Phone Number 771-5299
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock
Trading Symbol FSBW
Security Exchange Name NASDAQ
Entity, Emerging Growth Company false
Amendment Flag false
Entity, Central Index Key 0001530249