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FHLB Advances and Other Borrowings - Narrative (Details) | 12 Months Ended
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Sep. 30, 2020 USD ($)
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items] |
FHLB advances callable as of August 7, 2020 and quarterly thereafter | $ 100,000,000
Federal Home Loan Bank of Des Moines |
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items] |
Federal home loan bank, percent of assets | 45.00%

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- 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
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- Definition Par amount of advances made and reported by Federal Home Loan Bank (FHLBank) with the earlier of contractual maturity or next call date within the next rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References No definition available. + Details
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Balance Type: | debit
Period Type: | instant

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- Definition Federal Home Loan Bank, Line of Credit, Maximum Borrowing Capacity, Percentage of Assets + References No definition available. + Details
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Namespace Prefix: | wfsl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |