Commitments and Contingencies (Narrative) (Details) $ in Thousands	Sep. 30, 2023 USD ($)
Statement of Financial Position [Abstract]
Loan subsidies	$ 7,000
Commitment for focused community outreach and marketing efforts	$ 2,000

Loan subsidies that the Bank has committed to provide over a five-year period with the goal of increasing home mortgage loans, home improvement loans, and home refinance loans in specific census tracts in Rhode Island.

No definition available.

Name:	wash_LoanSubsidies
Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant