XML 11 R39.htm IDEA: XBRL DOCUMENT v2.4.1.9
Allowance for Losses on Loans - Impaired Loans Based on Loan Types (Details) (USD $)
In Thousands, unless otherwise specified
 6 Months Ended 12 Months Ended
Mar. 31, 2015
Sep. 30, 2014
Financing Receivable, Impaired [Line Items]    
Recorded Investment $ 385,651us-gaap_ImpairedFinancingReceivableRecordedInvestment $ 435,185us-gaap_ImpairedFinancingReceivableRecordedInvestment
Unpaid Principal Balance 413,940us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance 470,190us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Related Allowance 8,597us-gaap_ImpairedFinancingReceivableRelatedAllowance 10,587us-gaap_ImpairedFinancingReceivableRelatedAllowance
Average Recorded Investment 377,636us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 403,138us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Amount of related allowance included in specific reserves   60us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Amount of related allowance included in general reserves   10,527us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 45,560us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember		 46,680us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
Unpaid Principal Balance 66,459us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember		 73,123us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
Average Recorded Investment 41,076us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember		 37,474us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 340,091us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember		 388,505us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
Unpaid Principal Balance 347,481us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember		 397,067us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
Related Allowance 8,597us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember		 10,587us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
Average Recorded Investment 336,560us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember		 365,664us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
Single-Family Residential [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 314,115us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 346,364us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Unpaid Principal Balance 321,394us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 354,497us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Related Allowance 8,597us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 10,527us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Average Recorded Investment 310,630us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 333,191us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Single-Family Residential [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 23,164us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 24,044us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Unpaid Principal Balance 25,986us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 26,628us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Average Recorded Investment 21,135us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 16,843us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Single-Family Residential [Member] | Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 290,951us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 322,320us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Unpaid Principal Balance 295,408us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 327,869us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Related Allowance 8,597us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 10,527us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Average Recorded Investment 289,495us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember		 316,348us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Construction - Speculative [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 7,405us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 9,159us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Unpaid Principal Balance 8,390us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 10,159us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 60us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Average Recorded Investment 7,261us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 9,336us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Construction - Speculative [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 997us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 1,603us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Unpaid Principal Balance 1,192us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 2,173us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Average Recorded Investment 1,001us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 1,804us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Construction - Speculative [Member] | Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 6,408us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 7,556us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Unpaid Principal Balance 7,198us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 7,986us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 60us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Average Recorded Investment 6,260us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember		 7,532us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_ConstructionSpeculativeMember
Land - Acquisition & Development [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 4,864us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 5,533us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Unpaid Principal Balance 6,348us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 7,961us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Average Recorded Investment 4,946us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 5,152us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Land - Acquisition & Development [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 685us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 837us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Unpaid Principal Balance 1,229us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 2,325us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Average Recorded Investment 738us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 1,038us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Land - Acquisition & Development [Member] | Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 4,179us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 4,696us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Unpaid Principal Balance 5,119us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 5,636us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Average Recorded Investment 4,208us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember		 4,114us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandAcquisitionAndDevelopmentMember
Land - Consumer Lot Loans [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 13,854us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 13,976us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Unpaid Principal Balance 14,335us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 14,457us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Average Recorded Investment 13,520us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 13,571us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Land - Consumer Lot Loans [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 1,353us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 974us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Unpaid Principal Balance 1,451us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 1,072us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Average Recorded Investment 1,144us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 713us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Land - Consumer Lot Loans [Member] | Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 12,501us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 13,002us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Unpaid Principal Balance 12,884us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 13,385us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Average Recorded Investment 12,376us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember		 12,858us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_LandConsumerLotLoansMember
Multi-Family [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 4,941us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 6,354us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Unpaid Principal Balance 4,941us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 6,574us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Average Recorded Investment 4,627us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 5,284us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Multi-Family [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 1,079us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 1,111us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Unpaid Principal Balance 1,079us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 1,111us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Average Recorded Investment 1,080us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 327us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Multi-Family [Member] | Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 3,862us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 5,243us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Unpaid Principal Balance 3,862us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 5,463us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Average Recorded Investment 3,547us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember		 4,957us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_MultiFamilyHousingPortfolioSegmentMember
Commercial Real Estate [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 30,441us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 47,393us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Unpaid Principal Balance 35,468us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 55,113us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Average Recorded Investment 28,747us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 30,292us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Commercial Real Estate [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 9,768us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 13,234us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Unpaid Principal Balance 14,145us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 20,085us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Average Recorded Investment 9,587us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 11,720us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Commercial Real Estate [Member] | Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 20,673us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 34,159us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Unpaid Principal Balance 21,323us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 35,028us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Average Recorded Investment 19,160us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember		 18,572us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Commercial & Industrial [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 6,988us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember		 3,195us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember
Unpaid Principal Balance 18,865us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember		 17,166us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember
Average Recorded Investment 5,091us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember		 3,900us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember
Commercial & Industrial [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 6,988us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember		 3,195us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember
Unpaid Principal Balance 18,865us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember		 17,166us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember
Average Recorded Investment 5,091us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember		 3,900us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_CommercialAndIndustrialLoansMember
HELOC [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 2,506us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 2,505us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Unpaid Principal Balance 3,292us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 3,216us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Average Recorded Investment 2,321us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 1,816us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
HELOC [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 1,112us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 1,019us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Unpaid Principal Balance 1,898us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 1,730us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Average Recorded Investment 931us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 612us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
HELOC [Member] | Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 1,394us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 1,486us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Unpaid Principal Balance 1,394us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 1,486us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Average Recorded Investment 1,390us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember		 1,204us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= wfsl_HomeEquityLineOfCreditMember
Consumer [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 537us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 706us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Unpaid Principal Balance 907us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 1,047us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Average Recorded Investment 493us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 596us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Consumer [Member] | Financing Receivable, Impairment, No Related Allowance [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 414us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 663us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Unpaid Principal Balance 614us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 833us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Average Recorded Investment 369us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 517us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentNoRelatedAllowanceMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Consumer [Member] | Financing Receivable, Impairment, Allowance Recorded [Member]    
Financing Receivable, Impaired [Line Items]    
Recorded Investment 123us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 43us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Unpaid Principal Balance 293us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Average Recorded Investment $ 124us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember		 $ 79us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= wfsl_FinancingReceivableImpairmentAllowanceRecordedMember
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember