XML 94 R79.htm IDEA: XBRL DOCUMENT
v3.25.1

Note 5 - Mortgage Servicing Rights - Schedule of Sensitivity Analysis of Fair Value (Details) - Mortgage Servicing Rights [Member] - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023
Aggregate portfolio principal balance | $ 1,630,000 | $ 2,830,000
Conditional prepayment rate (“CPR”) | 8.30% | 7.20%
Fair value MSRs | $ 21,000 | $ 38,200
Weighted average discount rate | 10.20% | 9.40%
Base Rate [Member] |  |
Aggregate portfolio principal balance | $ 1,632,141 | $ 2,832,016
Weighted average rate of loans in MSRs portfolio | 4.20% | 3.60%
Base Rate [Member] | Measurement Input, Prepayment Rate [Member] |  |
Conditional prepayment rate (“CPR”) | 8.30% | 7.20%
Fair value MSRs | $ 21,043 | $ 38,163
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Other than 10 or 20 Percent Adverse Change in Other Assumption, Percent | 1.20% | 1.30%
Base Rate [Member] | Measurement Input, Discount Rate [Member] |  |
Fair value MSRs | $ 21,043 | $ 38,163
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Other than 10 or 20 Percent Adverse Change in Other Assumption, Percent | 1.30% | 1.30%
Weighted average discount rate | 10.20% | 9.40%
Sensitivity Analysis of Fair Value, Impact of 0.5 Percent Adverse Change in Other Assumption [Member] | Measurement Input, Prepayment Rate [Member] |  |
Conditional prepayment rate (“CPR”) | 10.10% | 8.00%
Fair value MSRs | $ 20,127 | $ 37,268
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Other than 10 or 20 Percent Adverse Change in Other Assumption, Percent | 1.20% | 1.30%
Sensitivity Analysis of Fair Value, Impact of 0.5 Percent Adverse Change in Other Assumption [Member] | Measurement Input, Discount Rate [Member] |  |
Fair value MSRs | $ 20,587 | $ 37,301
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Other than 10 or 20 Percent Adverse Change in Other Assumption, Percent | 1.30% | 1.30%
Weighted average discount rate | 10.70% | 9.90%
Sensitivity Analysis of Fair Value, Impact of 1.0 Percent Adverse Change in Other Assumption [Member] | Measurement Input, Prepayment Rate [Member] |  |
Conditional prepayment rate (“CPR”) | 12.70% | 9.30%
Fair value MSRs | $ 19,067 | $ 35,819
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Other than 10 or 20 Percent Adverse Change in Other Assumption, Percent | 1.10% | 1.30%
Sensitivity Analysis of Fair Value, Impact of 1.0 Percent Adverse Change in Other Assumption [Member] | Measurement Input, Discount Rate [Member] |  |
Fair value MSRs | $ 20,149 | $ 36,476
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Other than 10 or 20 Percent Adverse Change in Other Assumption, Percent | 1.20% | 1.30%
Weighted average discount rate | 11.20% | 10.40%

X
- Definition The face amount of financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
Name: | us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Yield on the receivable, on which interest has been imputed, as calculated from its issuance value or purchase price. The calculated effective interest rate considers factors such as the issued face value or price paid for the receivable, the time period between payments, and the time until maturity [full receipt] of the receivable. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482949/835-30-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482900/835-30-50-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482925/835-30-45-2 + Details
Name: | us-gaap_ReceivableWithImputedInterestEffectiveYieldInterestRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition A specified percentage variance in a specified key assumption in the determination of fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 860 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481326/860-20-50-4 + Details
Name: | us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfOtherThan10Or20PercentAdverseChangeInOtherAssumptionPercent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481229/860-50-50-3 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481260/860-50-45-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481260/860-50-45-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481260/860-50-45-2 + Details
Name: | us-gaap_ServicingAssetAtFairValueAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Discount rate used to estimate the fair value of servicing assets and servicing liabilities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481229/860-50-50-2 + Details
Name: | us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Estimated rate of prepayments of principal on servicing assets and servicing liabilities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481229/860-50-50-2 + Details
Name: | us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValuePrepaymentSpeed
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fsbw_MortgageServicingRightsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_BaseRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPrepaymentRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=fsbw_SensitivityAnalysisOfFairValueImpactOf05PercentAdverseChangeInOtherAssumptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=fsbw_SensitivityAnalysisOfFairValueImpactOf10PercentAdverseChangeInOtherAssumptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |