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Allowance for Losses on Loans - Credit Risk Profile Based on Payment Activity (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	$ 8,793,428us-gaap_LoansAndLeasesReceivableGrossCarryingAmount	$ 8,669,717us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Nonaccrual loans by portfolio segment	98,353us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest	87,431us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest	114,717us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest
Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	8,439,849us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	8,321,591us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	98.80%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	164,317us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember		197,910us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as percentage of total gross loans	1.13%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember		1.37%wfsl_GradeAsPercentageOfTotalGrossLoans / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Nonaccrual loans by portfolio segment	98,353us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	87,431us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	1.20%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	5,619,694us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember	5,572,244us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Nonaccrual loans by portfolio segment	74,416us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember	74,067us-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	5,533,792us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	5,486,136us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	98.70%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	74,416us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	74,067us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	1.30%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	152,450us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember	140,060us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember
Nonaccrual loans by portfolio segment	1,329us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember	1,477us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember
Construction - Speculative [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	151,121us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	138,583us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	99.10%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	1,329us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	1,477us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	0.90%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	377,561us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember	385,824us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember
Construction - Custom [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	377,561us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	385,824us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross 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	0us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	0us-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	86,405us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember	80,359us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember
Nonaccrual loans by portfolio segment	0us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember	811us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember
Land - Acquisition & Development [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	84,000us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	77,021us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross 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	0us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	811us-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	106,988us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember	111,130us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember
Nonaccrual loans by portfolio segment	2,260us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember	2,637us-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	102,232us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	105,986us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	97.80%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	2,260us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	2,637us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	2.20%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	980,706us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember	920,285us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember
Nonaccrual loans by portfolio segment	1,019us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember	1,742us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember
Multi-Family [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	976,733us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	915,544us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	99.90%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	1,019us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	1,742us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	0.10%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	749,856us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember	752,957us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember
Nonaccrual loans by portfolio segment	15,970us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember	5,106us-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	581,466us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	586,230us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	97.30%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	15,970us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	5,106us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	2.70%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	453,418us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember	434,088us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember
Nonaccrual loans by portfolio segment	672us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember	7us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember
Commercial & Industrial [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	390,655us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	379,219us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	99.80%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	672us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	7us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	0.20%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	134,998us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember	134,455us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember
Nonaccrual loans by portfolio segment	1,454us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember	795us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember
HELOC [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	116,593us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	115,247us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	98.80%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	1,454us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	795us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	1.20%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	131,352us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember	138,315us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Nonaccrual loans by portfolio segment	1,233us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember	789us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Consumer [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	125,696us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember	131,801us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Grade as percentage of total gross loans	99.00%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	$ 1,233us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember	$ 789us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Grade as a percentage of total gross loans	1.00%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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+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

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