XML 52 R43.htm IDEA: XBRL DOCUMENT
v3.22.2

Derivatives and Hedging Activities - Additional Information (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021
Derivative [Line Items] |  |  |  |
Gain (loss) on termination of hedging derivatives | $ 0 | $ 0 | $ 0 | $ 14,110
Interest Rate Swap | Minimum |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative, maturities |  |  | 2 years |
Interest Rate Swap | Maximum |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative, maturities |  |  | 8 years |
Interest Rate Swap | Weighted average |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative, maturities |  |  | 6 years 9 months 18 days |
Interest Rate Swap One | Designated as Hedging Instrument | Cash flow hedging |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount of derivative terminated |  |  |  | $ 400,000
Effective interest rate of derivative terminated |  |  |  | 2.15%
Interest Rate Swap Two | Designated as Hedging Instrument | Cash flow hedging |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount of derivative terminated |  |  |  | $ 200,000
Effective interest rate of derivative terminated |  |  |  | 0.79%
Interest Rate Swap Three | Designated as Hedging Instrument | Cash flow hedging |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount of derivative terminated |  |  |  | $ 150,000
Effective interest rate of derivative terminated |  |  |  | 2.91%

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DerivativeRemainingMaturity1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Derivative Terminated, Effective Interest Rate + References No definition available. + Details
Name: | wfsl_DerivativeTerminatedEffectiveInterestRate
Namespace Prefix: | wfsl_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Derivative Terminated, Notional Amount + References No definition available. + Details
Name: | wfsl_DerivativeTerminatedNotionalAmount
Namespace Prefix: | wfsl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Gain (Loss) on Terminated Derivative Instruments, Net, Pretax + References No definition available. + Details
Name: | wfsl_GainLossOnTerminatedDerivativeInstrumentsNetPretax
Namespace Prefix: | wfsl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=wfsl_InterestRateSwapOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=wfsl_InterestRateSwapTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=wfsl_InterestRateSwapThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |