Securities (Narrative) (Details) $ in Thousands	6 Months Ended
Jun. 30, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Accrued interest receivable	$ 3,600	$ 3,700
Amortized cost of callable debt securities	252,900
Fair value of callable debt securities	$ 226,700
Available for sale debt securities, securities in continuous unrealized loss position, number of securities \| security	195	190
Available for sale debt securities, fair value	$ 951,828	$ 1,000,380
Asset Pledged as Collateral
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Available for sale debt securities, fair value	$ 298,900	$ 311,900
Individual name issuer trust preferred debt securities
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Available for sale debt securities, securities in continuous unrealized loss position, number of securities \| security	3	3
Securities in unrealized loss position, number of companies issuing securities \| security	3
Number of debt securities below investment grade \| security	1
Amortized cost of securities below investment grade	$ 2,000
Unrealized losses on securities below investment grade	(176)
Available for sale debt securities, fair value	$ 9,101	$ 8,793
Corporate bonds [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Available for sale debt securities, securities in continuous unrealized loss position, number of securities \| security	4	4
Securities in unrealized loss position, number of companies issuing securities \| security	3
Number of debt securities below investment grade \| security	1
Amortized cost of securities below investment grade	$ 2,000
Unrealized losses on securities below investment grade	(35)
Available for sale debt securities, fair value	$ 12,456	$ 11,889
Minimum [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Maturity period of callable debt securities	1 year
Call features of callable debt securities	1 month
Maximum [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Maturity period of callable debt securities	13 years
Call features of callable debt securities	5 months

Interest, dividends, rents, ancillary and other revenues earned but not yet received by the entity on its investments.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

+ Details

Name:	us-gaap_AccruedInvestmentIncomeReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-4

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The amortized cost of debt securities that are below investment grade as of the balance sheet date.

+ References

No definition available.

+ Details

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

- Definition

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Companies Issuing Securities

+ References

No definition available.

+ Details

Name:	wash_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfCompaniesIssuingSecurities
Namespace Prefix:	wash_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

This represents the amortized cost for callable debt securities.

+ References

No definition available.

+ Details

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

- Definition

Callable Debt Securities, Call Feature, Period

+ References

No definition available.

+ Details

Name:	wash_CallableDebtSecuritiesCallFeaturePeriod
Namespace Prefix:	wash_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

This represents the fair value for callable debt securities.

+ References

No definition available.

+ Details

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

- Definition

Callable Debt Securities, Maturity Period

+ References

No definition available.

+ Details

Name:	wash_CallableDebtSecuritiesMaturityPeriod
Namespace Prefix:	wash_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of debt securities below investment grade

+ References

No definition available.

+ Details

Name:	wash_NumberOfDebtSecuritiesBelowInvestmentGrade
Namespace Prefix:	wash_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items for schedule of Available for Sale and Held to Maturty Securities.

+ References

No definition available.

+ Details

Name:	wash_ScheduleOfAvailableForSaleAndHeldToMaturtySecuritiesLineItems
Namespace Prefix:	wash_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The unrealized losses of debt securities that are below investment grade as of the balance sheet date.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_PledgedStatusAxis=us-gaap_AssetPledgedAsCollateralMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=wash_TrustPreferredSecuritiesIndividualNameIssuersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateBondSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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