Loans (Narrative) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Loans Receivable Net Deferred Cost Originated	$ 2,200,000	$ 2,100,000
Loans Receivable Net Deferred Premium on Purchased Loans	92,000	94,000
Loans Pledged as Collateral	1,240,000,000us-gaap_LoansPledgedAsCollateral	1,210,000,000us-gaap_LoansPledgedAsCollateral
Past Due Loans on Nonaccrual	$ 12,300,000wash_LoansReceivablePastDueNonaccrual	$ 12,700,000wash_LoansReceivablePastDueNonaccrual

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5086-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6467456&loc=d3e113888-111728

+ Details

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

- Details

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

- Definition

Reflects cumulative amount of net costs paid by borrowers which have not been taken into expense.

+ References

No definition available.

+ Details

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

- Definition

Reflects premiums over or discounts from face amounts of acquired loans that are being amortized into income as an adjustment to yield.

+ References

No definition available.

+ Details

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

- Definition

Reflects carrying value of loans which are past due and on nonaccrual status.

+ References

No definition available.

+ Details

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