Defined Benefit Pension Plans (Narrative) (Details)	120 Months Ended
Dec. 31, 2023
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Transition Period Pension Plan Amendment	10 years

The period in which pension plans amendments will transition.

No definition available.

Name:	wash_TransitionPeriodPensionPlanAmendment
Namespace Prefix:	wash_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration