Derivative Financial Instruments (Narrative) (Details) $ in Millions	Mar. 31, 2023 USD ($)
Statement of Financial Position [Abstract]
Loss on cash flow hedge included in AOCI(L) upon termination	$ 26.5
Loss on cash flow hedge included in AOCI(L) upon termination, net of tax	$ 20.1

The amount of the loss on a cash flow hedge that is included in AOCI(L), upon termination of the cash flow hedge, and that will be amortized into earnings over the remaining life of the original cash flow hedge term.

No definition available.

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