XML 58 R48.htm IDEA: XBRL DOCUMENT
v3.20.2

Derivatives and Hedging Activities - Impact of Fair Value Hedge Accounting on the Carrying Value of the Hedged Items (Details) - USD ($) $ in Thousands | Jun. 30, 2020 | Sep. 30, 2019
--- | --- | ---
Derivatives, Fair Value [Line Items] |  |
Carrying value of hedged items | $ 2,855,203 | $ 1,612,208
Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items | 26,830 | 2,680
Mortgage loan fair value hedges |  |
Derivatives, Fair Value [Line Items] |  |
Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items | 17,605 | (1,608)
Amortized cost basis of the hedged loans |  | 200,000
Commercial loan fair value hedges |  |
Derivatives, Fair Value [Line Items] |  |
Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items | 9,225 | 4,288
Loans Receivable |  |
Derivatives, Fair Value [Line Items] |  |
Carrying value of hedged items | 2,855,203 | 1,612,208
Cumulative gain (loss) fair value hedge adjustment included in carrying amount of hedged items | 26,830 | 2,680
Loans Receivable | Mortgage loan fair value hedges |  |
Derivatives, Fair Value [Line Items] |  |
Carrying value of hedged items | 2,752,843 | 1,520,647
Loans Receivable | Commercial loan fair value hedges |  |
Derivatives, Fair Value [Line Items] |  |
Carrying value of hedged items | $ 102,360 | $ 91,561

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

X
- Definition Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4EE -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL109999712-113959 + Details
Name: | us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of asset hedged in last of layer, expected to be remaining at end of hedging relationship. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4EEE -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL109999718-113959 + Details
Name: | us-gaap_HedgedAssetFairValueHedgeLastOfLayerAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of liability hedged in fair value hedging relationship. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4EE -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL109999712-113959 + Details
Name: | us-gaap_HedgedLiabilityFairValueHedge
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=wfsl_MortgageLoanHedgeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=wfsl_CommercialLoanHedgeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_LoansReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |