XML 39 R29.htm IDEA: XBRL DOCUMENT
v3.19.1

Loans Receivable - Loan Modifications (Details) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Mar. 31, 2019 USD ($) contract | Mar. 31, 2018 USD ($) contract | Mar. 31, 2019 USD ($) contract | Mar. 31, 2018 USD ($) contract
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Contracts | contract | 4 | 1 | 5 | 2
Recorded Investment | $ | $ 755 | $ 162 | $ 1,298 | $ 206
Single-family residential |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Number of Contracts | contract | 4 | 1 | 5 | 2
Recorded Investment | $ | $ 755 | $ 162 | $ 1,298 | $ 206

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Modifications, Number of Contracts that Subsequently Defaulted + References No definition available. + Details
Name: | wfsl_FinancingReceivableModificationsNumberOfContractsThatSubsequentlyDefaulted
Namespace Prefix: | wfsl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing Receivable, Modifications, Recorded Investment During the Period + References No definition available. + Details
Name: | wfsl_FinancingReceivableModificationsRecordedInvestmentDuringPeriod
Namespace Prefix: | wfsl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |