XML 38 R36.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Allowance for Losses on Loans - Loans Evaluated for Impairment (Details) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013
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Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | $ 108,323 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 108,700 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 112,347 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 114,931 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 118,158 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 116,741 us-gaap_FinancingReceivableAllowanceForCreditLosses
Loans receivable, gross | 9,014,755 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount |  | 8,669,717 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount |  |  |
Single-Family Residential [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 54,762 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 55,495 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 62,763 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 63,348 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 67,692 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 64,184 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
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 |  |  |
Construction - Speculative [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 5,445 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 5,451 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 6,742 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 6,773 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 8,142 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 8,407 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember
Loans receivable, gross | 163,657 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  | 140,060 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  |  |
Construction - Custom [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 968 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember | 965 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember | 1,695 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember | 1,599 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember | 1,474 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember | 882 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember
Loans receivable, gross | 370,693 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  | 385,824 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  |  |
Land - Acquisition & Development [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 7,405 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 6,671 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 5,592 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 6,027 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 7,084 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 9,165 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember
Loans receivable, gross | 107,181 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  | 80,359 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  |  |
Land - Consumer Lot Loans [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 3,035 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 3,113 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 3,077 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 2,974 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 3,274 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 3,552 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember
Loans receivable, gross | 104,558 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  | 111,130 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  |  |
Multi-Family [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 4,673 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 4,500 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 4,248 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 4,187 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 4,109 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 3,816 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember
Loans receivable, gross | 1,012,915 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  | 920,285 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  |  |
Commercial Real Estate [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 6,734 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 5,872 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 7,548 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 5,924 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 5,868 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 5,595 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember
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 |  |  |
Commercial & Industrial [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 21,146 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 23,328 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 16,527 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 20,403 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 16,505 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 16,614 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember
Loans receivable, gross | 466,207 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  | 434,088 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  |  |
HELOC [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 850 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 892 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 928 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 975 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 943 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 1,002 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember
Loans receivable, gross | 136,439 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  | 134,455 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  |  |
Consumer [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 3,305 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 2,413 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 3,227 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 2,721 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 3,067 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 3,524 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
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 |  |  |
Loans Collectively Evaluated for Impairment [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 108,323 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember |  | 112,287 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember |  |  |
Loans receivable, gross | 8,287,193 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember |  | 8,316,874 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember |  |  |
Ratio | 1.30%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember |  | 1.40%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Single-Family Residential [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 54,762 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  | 62,067 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  |  |
Loans receivable, gross | 5,476,667 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  | 5,487,331 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  |  |
Ratio | 1.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  | 1.10%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Construction - Speculative [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 5,445 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  | 6,682 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  |  |
Loans receivable, gross | 97,987 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  | 130,901 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  |  |
Ratio | 5.60%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  | 5.50%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Construction - Custom [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 968 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  | 1,695 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  |  |
Loans receivable, gross | 201,777 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  | 385,464 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  |  |
Ratio | 0.50%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  | 0.50%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Land - Acquisition & Development [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 7,405 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  | 5,592 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  |  |
Loans receivable, gross | 87,541 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  | 73,999 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  |  |
Ratio | 8.50%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  | 7.60%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Land - Consumer Lot Loans [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 3,035 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  | 3,077 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  |  |
Loans receivable, gross | 89,279 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  | 95,684 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  |  |
Ratio | 3.40%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  | 3.20%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Multi-Family [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 4,673 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  | 4,248 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  |  |
Loans receivable, gross | 936,010 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  | 911,162 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  |  |
Ratio | 0.50%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  | 0.50%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Commercial Real Estate [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 6,734 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  | 7,548 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  |  |
Loans receivable, gross | 617,633 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  | 563,534 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  |  |
Ratio | 1.10%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  | 1.40%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Commercial & Industrial [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 21,146 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  | 17,223 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  |  |
Loans receivable, gross | 442,459 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  | 421,816 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  |  |
Ratio | 4.80%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  | 4.60%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | HELOC [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 850 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  | 928 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  |  |
Loans receivable, gross | 119,235 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  | 114,393 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  |  |
Ratio | 0.70%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  | 0.90%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  |  |
Loans Collectively Evaluated for Impairment [Member] | Consumer [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 3,305 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 3,227 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  |  |
Loans receivable, gross | 218,605 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 132,590 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  |  |
Ratio | 1.50%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 2.40%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  |  |
Loans Individually Evaluated for Impairment [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember |  | 60 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember |  |  |
Loans receivable, gross | 96,398 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember |  | 134,736 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Single-Family Residential [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  |  |
Loans receivable, gross | 55,886 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  | 72,869 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Construction - Speculative [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  | 60 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  |  |
Loans receivable, gross | 7,405 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  | 9,159 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  | 0.70%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Construction - Custom [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  |  |
Loans receivable, gross | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  | 360 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Land - Acquisition & Development [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  |  |
Loans receivable, gross | 3,298 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  | 3,833 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Land - Consumer Lot Loans [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  |  |
Loans receivable, gross | 12,723 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  | 12,939 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Multi-Family [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  |  |
Loans receivable, gross | 5,112 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  | 6,124 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Commercial Real Estate [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  |  |
Loans receivable, gross | 10,210 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  | 27,802 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Commercial & Industrial [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  |  |
Loans receivable, gross | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember |  |  |
Loans Individually Evaluated for Impairment [Member] | HELOC [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  |  |
Loans receivable, gross | 1,669 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  | 1,650 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember |  |  |
Loans Individually Evaluated for Impairment [Member] | Consumer [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for probable losses | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  |  |
Loans receivable, gross | $ 95 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | $ 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  |  |
Ratio | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 0.00%wfsl_AllowanceAsPercentageOfOutstandingLoansAndLeases / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  |  |

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