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Number of financing receivables that have been modified by troubled debt restructurings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

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Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

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Reflects the amount of the write-down related to a troubled debt restructuring.

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Financing Receivable, Impaired, Troubled Debt Restructuring, Percent of Restructured Loans Performing

No definition available.

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Loan Modification, Basis Point Reduction, Maximum

No definition available.

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Loan Modification, Basis Point Reduction, Minimum

No definition available.

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Single Family Residential Loans as Percentage of Restructured Loans

No definition available.

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Term for Payment and Rate Reduction

No definition available.

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Namespace Prefix:	wfsl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConstructionLoansMember
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Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=wfsl_LandConsumerLotLoansMember
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Data Type:	na
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Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_HomeEquityMember
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