XML 165 R91.htm IDEA: XBRL DOCUMENT
v3.23.3

Employee Benefit Plans - Schedule of vesting by participant age (Details) - SERP | 12 Months Ended
--- | ---
Sep. 30, 2023
Before 62 |
Defined Benefit Plan Disclosure [Line Items] |
Vested Percentage | 0.00%
62 |
Defined Benefit Plan Disclosure [Line Items] |
Vested Percentage | 80.00%
63 |
Defined Benefit Plan Disclosure [Line Items] |
Vested Percentage | 90.00%
64 |
Defined Benefit Plan Disclosure [Line Items] |
Vested Percentage | 100.00%

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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Contribution Plan, Vesting Percentage + References No definition available. + Details
Name: | wfsl_DefinedContributionPlanVestingPercentage
Namespace Prefix: | wfsl_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | wfsl_DefinedContributionPlanVestingAxis=wfsl_DefinedContributionPlanVestingTrancheOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | wfsl_DefinedContributionPlanVestingAxis=wfsl_DefinedContributionPlanVestingTrancheTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | wfsl_DefinedContributionPlanVestingAxis=wfsl_DefinedContributionPlanVestingTrancheThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | wfsl_DefinedContributionPlanVestingAxis=wfsl_DefinedContributionPlanVestingTrancheFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |