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Data Type:	xbrli:stringItemType
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Period Type:	duration

Amount, after troubled debt restructuring, of modified financing receivable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

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Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18794-111554

Name:	us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Financing Receivables, Percent of Troubled Debt Restructuring Classified as 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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Balance Type:	na
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Loans and Leases Receivable, Impaired, Nonperforming, Nonaccrual Interest Income Recognized

No definition available.

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Namespace Prefix:	wfsl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Single Family Residential Loans as Percentage of Restructured Loans

No definition available.

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Namespace Prefix:	wfsl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Term for Payment and Rate Reduction

No definition available.