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v2.4.1.9

Allowance for Losses on Loans - Loans Collectively and Individually Evaluated for Impairment (Details) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Sep. 30, 2014 | Sep. 30, 2013
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Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Allowance for probable losses | $ 108,700 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 112,347 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 116,741 us-gaap_FinancingReceivableAllowanceForCreditLosses
Loans receivable, gross | 8,793,428 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 | 55,495 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 62,763 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 64,184 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Loans receivable, gross | 5,619,694 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 | 5,451 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 6,742 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember | 8,407 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionSpeculativeMember
Loans receivable, gross | 152,450 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 | 965 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember | 1,695 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember | 882 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_ConstructionCustomMember
Loans receivable, gross | 377,561 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 | 6,671 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 5,592 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember | 9,165 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandAcquisitionAndDevelopmentMember
Loans receivable, gross | 86,405 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 | 3,113 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 3,077 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember | 3,552 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_LandConsumerLotLoansMember
Loans receivable, gross | 106,988 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 | 4,500 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 4,248 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember | 3,816 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_MultiFamilyHousingPortfolioSegmentMember
Loans receivable, gross | 980,706 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 | 5,872 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 7,548 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember | 5,595 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstatePortfolioSegmentMember
Loans receivable, gross | 749,856 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 | 23,328 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 16,527 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember | 16,614 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_CommercialAndIndustrialLoansMember
Loans receivable, gross | 453,418 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 | 892 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 928 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember | 1,002 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = wfsl_HomeEquityLineOfCreditMember
Loans receivable, gross | 134,998 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 | 2,413 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 3,227 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 3,524 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Loans receivable, gross | 131,352 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 | 108,700 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember | 112,287 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember |
Loans receivable, gross | 8,084,922 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember | 8,316,874 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansCollectivelyEvaluatedForImpairmentMember |
Allowance as a percentage of outstanding loans and leases | 1.40%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 | 55,495 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 | 5,542,825 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 5,451 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 | 87,711 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 |
Allowance as a percentage of outstanding loans and leases | 6.20%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 | 965 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 | 191,787 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 6,671 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 | 66,953 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 |
Allowance as a percentage of outstanding loans and leases | 10.00%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 | 3,113 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 | 91,588 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 4,500 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 | 901,277 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 5,872 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 | 533,593 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 23,328 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 | 425,724 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 |
Allowance as a percentage of outstanding loans and leases | 5.40%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 | 892 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 | 116,544 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 |
Allowance as a percentage of outstanding loans and leases | 0.80%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 | 2,413 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 | 126,920 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 |
Allowance as a percentage of outstanding loans and leases | 1.90%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 | 119,840 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember | 134,736 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = wfsl_LoansIndividuallyEvaluatedForImpairmentMember |
Allowance as a percentage of outstanding loans and leases | 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 | 63,091 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 7,656 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 |
Allowance as a percentage of outstanding loans and leases | 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 3,394 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 12,856 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 5,019 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 26,217 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 |
Allowance as a percentage of outstanding loans and leases | 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 |
Allowance as a percentage of outstanding loans and leases | 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 | 1,598 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 |
Allowance as a percentage of outstanding loans and leases | 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 | $ 9 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 |
Allowance as a percentage of outstanding loans and leases | 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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