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v2.4.1.9

Allowance for Losses on Loans - Credit Risk Profile Based on Payment Activity (Details) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Sep. 30, 2014
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Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | $ 9,014,755 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount | $ 8,669,717 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Nonaccrual loans by portfolio segment | 75,850 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest | 87,431 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest
Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 8,698,778 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 8,321,591 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 99.10%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 143,223 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 147,311 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Total grade as a % of total net loans | 0.98%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 1.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Nonaccrual loans by portfolio segment | 76,895 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 87,431 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 0.90%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 1.00%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Single-Family Residential [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 5,546,403 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 5,572,244 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Nonaccrual loans by portfolio segment | 59,948 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 74,067 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Single-Family Residential [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 5,474,323 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 5,486,136 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 98.90%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 98.70%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Single-Family Residential [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 60,781 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 74,067 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 1.10%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 1.30%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Construction - Speculative [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 163,657 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 140,060 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember
Nonaccrual loans by portfolio segment | 1,152 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 1,477 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember
Construction - Speculative [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 162,505 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 138,583 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 99.30%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 98.90%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Construction - Speculative [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 1,152 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 1,477 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 0.70%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 1.10%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Construction - Custom [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 370,693 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember | 385,824 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember
Construction - Custom [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 370,693 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 385,824 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 100.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 100.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Construction - Custom [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 0 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 0.00%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.00%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Land - Acquisition & Development [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 107,181 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 80,359 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember
Nonaccrual loans by portfolio segment | 0 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 811 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember
Land - Acquisition & Development [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 105,058 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 77,021 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 100.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Land - Acquisition & Development [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 0 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 811 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 0.00%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 1.00%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Land - Consumer Lot Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 104,558 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 111,130 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember
Nonaccrual loans by portfolio segment | 2,246 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 2,637 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember
Land - Consumer Lot Loans [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 99,624 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 105,986 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 97.60%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 97.60%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Land - Consumer Lot Loans [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 2,458 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 2,637 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 2.40%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 2.40%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Multi-Family [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 1,012,915 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 920,285 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember
Nonaccrual loans by portfolio segment | 0 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 1,742 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember
Multi-Family [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 1,010,003 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 915,544 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 100.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.80%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Multi-Family [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 0 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 1,742 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 0.00%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.20%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Commercial Real Estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 885,177 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 752,957 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember
Nonaccrual loans by portfolio segment | 5,735 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 5,106 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember
Commercial Real Estate [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 735,402 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 586,230 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 99.20%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.10%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Commercial Real Estate [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 5,735 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 5,106 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 0.80%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.90%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Commercial & Industrial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 466,207 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 434,088 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember
Nonaccrual loans by portfolio segment | 5,018 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 7 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember
Commercial & Industrial [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 403,340 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 379,219 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 98.80%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 100.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Commercial & Industrial [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 5,018 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 7 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 1.20%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.00%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
HELOC [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 136,439 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 134,455 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember
Nonaccrual loans by portfolio segment | 1,175 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 795 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember
HELOC [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 119,726 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 115,247 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 99.00%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.30%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
HELOC [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | 1,175 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 795 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 1.00%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.70%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Consumer [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 221,525 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 138,315 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Nonaccrual loans by portfolio segment | 576 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 789 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Consumer [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans receivable, gross | 218,104 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 131,801 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Total grade as a % of total net loans | 99.70%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.40%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Consumer [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Nonaccrual loans by portfolio segment | $ 576 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | $ 789 us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans | 0.30%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.60%us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember

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