Loans (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Receivables [Abstract]
Loans Receivable Net Deferred Cost Originated	$ 2,700	$ 2,100
Loans Receivable Net Deferred Premium on Purchased Loans	87	94
Loans Pledged as Collateral	1,270,000	1,210,000
Past Due Loans on Nonaccrual	14,000	$ 12,700
Nonaccrual Residential Real Estate Mortgaga Loans and Consumer Loans Classified as Impaired	$ 7,800

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 860

-SubTopic 30

-Section 45

-Paragraph 1

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

Reference 2: 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=49124121&loc=d3e5086-111524

+ Details

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

- References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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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

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Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Based on the redefinition of impaired loans, the amount of nonaccrual residential real estate mortgage loans and consumers loans that are classified as impaired at the end of the reporting period.

+ References

No definition available.

+ Details

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Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
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