XML 57 R47.htm IDEA: XBRL DOCUMENT v3.20.4

Revenue from Contracts with Customers - Additional Information (Details)	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue streams percentage, contract with customer	5.40%	4.40%

X

- References

No definition available.

+ Details

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

X

- Definition

Revenue From Contract With Customer, Percentage

+ References

No definition available.

+ Details

Name:	wfsl_RevenueFromContractWithCustomerPercentage
Namespace Prefix:	wfsl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration