XML 53 R43.htm IDEA: XBRL DOCUMENT v3.20.4

Derivatives and Hedging Activities - Additional Information (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2020 USD ($)
Minimum
Derivative [Line Items]
Derivative, maturities	1 year
Maximum
Derivative [Line Items]
Derivative, maturities	9 years
Weighted average
Derivative [Line Items]
Derivative, maturities	6 years 9 months 18 days
Cash flow hedging
Derivative [Line Items]
Notional amount of derivative terminated	$ 100,000
Effective interest rate of derivative terminated	1.39%

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

X

- Definition

Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeRemainingMaturity1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Derivative Terminated, Effective Interest Rate

+ References

No definition available.

+ Details

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

X

- Definition

Derivative Terminated, Notional Amount

+ References

No definition available.

+ Details

Name:	wfsl_DerivativeTerminatedNotionalAmount
Namespace Prefix:	wfsl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: