Loans (Narrative - Troubled Debt Restructurings) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Recorded investment in troubled debt restructurings	$ 17,700,000	$ 18,400,000
Interest Receivable	30,000us-gaap_InterestReceivable	33,000us-gaap_InterestReceivable
Specific Reserves on Troubled Debt Restructurings	$ 1,500,000	$ 1,200,000

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 40

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.8)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 8

-Article 5

+ Details

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Balance Type:	debit
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- Details

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- Definition

The amount of specific reserves on troubled debt restructurings.

+ References

No definition available.

+ Details

Name:	wash_SpecificReservesonTroubledDebtRestructurings
Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant