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Note 15 - Business Segments - Schedule of Segment Financial Results (Details) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2024 USD ($) | Mar. 31, 2023 USD ($)
Net interest income | [1] | $ 30,346 |  | $ 30,662 |
(Provision) recovery for credit losses |  | (1,399) |  | (2,108) |
Noninterest income |  | 5,111 | [2] | 5,219 | [3]
Noninterest expense | [4] | (23,529) |  | (23,524) |
Income before provision for income taxes |  | 10,529 |  | 10,249 |
Provision for income taxes |  | (2,132) |  | (2,037) |
Net income |  | 8,397 |  | 8,212 |
Total average assets for period ended |  | $ 2,958,547 |  | $ 2,742,026 |
Number of Employees, Geographic Area [Member] |  |  |  |  |
Full-time employees ("FTEs") |  | 570 |  | 586 |
Commercial And Consumer Banking [Member] |  |  |  |  |
Net interest income | [1] | $ 28,086 |  | $ 27,500 |
(Provision) recovery for credit losses |  | (1,251) |  | (2,122) |
Noninterest income |  | 2,393 | [2] | 2,380 | [3]
Noninterest expense | [4] | (19,008) |  | (18,610) |
Income before provision for income taxes |  | 10,220 |  | 9,148 |
Provision for income taxes |  | (2,069) |  | (1,809) |
Net income |  | 8,151 |  | 7,339 |
Total average assets for period ended |  | $ 2,401,864 |  | $ 2,250,052 |
Commercial And Consumer Banking [Member] | Number of Employees, Geographic Area [Member] |  |  |  |  |
Full-time employees ("FTEs") |  | 440 |  | 445 |
Home Lending [Member] |  |  |  |  |
Net interest income | [1] | $ 2,260 |  | $ 3,162 |
(Provision) recovery for credit losses |  | (148) |  | 14 |
Noninterest income |  | 2,718 | [2] | 2,839 | [3]
Noninterest expense | [4] | (4,521) |  | (4,914) |
Income before provision for income taxes |  | 309 |  | 1,101 |
Provision for income taxes |  | (63) |  | (228) |
Net income |  | 246 |  | 873 |
Total average assets for period ended |  | $ 556,683 |  | $ 491,974 |
Home Lending [Member] | Number of Employees, Geographic Area [Member] |  |  |  |  |
Full-time employees ("FTEs") |  | 130 |  | 141 |
[1] | Net interest income is the difference between interest earned on assets and the cost of liabilities to fund those assets. Interest earned includes actual interest earned on segment assets and, if the segment has excess liabilities, interest credits for providing funding to the other segment. The cost of liabilities includes interest expense on segment liabilities and, if the segment does not have enough liabilities to fund its assets, a funding charge based on the cost of assigned liabilities to fund segment assets.
[2] | Noninterest income includes activity from certain residential mortgage loans that were initially originated for sale and measured at fair value, and subsequently transferred to loans held for investment. Gains and losses from changes in fair value for these loans are reported in earnings as a component of noninterest income. For the three months ended March 31, 2024, the Company recorded a net increase in fair value of $2,000, as compared to a net increase in fair value of $577,000 for the three months ended March 31, 2023, respectively. As of March 31, 2024 and 2023, there was $15.0 million and $15.1 million, respectively, in residential mortgage loans recorded at fair value as they were previously transferred from loans held for sale to loans held for investment.
[3] | Noninterest income includes activity from certain residential mortgage loans that were initially originated for sale and measured at fair value, and subsequently transferred to loans held for investment. Gains and losses from changes in fair value for these loans are reported in earnings as a component of noninterest income. For the years ended December 31, 2023, 2022, and 2021, the Company recorded net increases in fair value of $447,000, net decreases of $1.7 million, and net decreases of $29,000, respectively. As of December 31, 2023, 2022, and 2021, there were $15.1 million, $14.0 million, and $17.8 million, respectively, in residential mortgage loans recorded at fair value as they were previously transferred from loans held for sale to loans held for investment.
[4] | Noninterest expense includes allocated overhead expense from general corporate activities. Allocation is determined based on a combination of segment assets and FTEs. For the three months ended March 31, 2024 and 2023, the Home Lending segment included allocated overhead expenses of $1.5 million and $1.6 million, respectively.

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Name: | us-gaap_StatementBusinessSegmentsAxis=fsbw_HomeLendingMember
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Data Type: | na
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Period Type: |