Sale of Business Line (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Sale of Business Line [Abstract]
Gain on sale of business line		$ 6,300,000
Gain on Sale of Business Line, After-Tax		4,000,000
Gain on Sale of Business Line, Earnings Per Share		$ 0.24
Divestiture Related Costs		355,000wash_DivestitureCosts
Divestiture Related Costs, After Tax		227,000wash_DivestitureCostsAfterTax
Earnings Per Share, Divestiture Costs		$ 0.01wash_DivestitureCostsEarningsPerShare
Net proceeds from sale of business line	0	7,205,000
Increase Decrease In Deferred Revenue From Sale Of Business Line		900,000
Deferred Merchant Referral Revenue remaining	$ 720,000

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfBusinesses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of deferred merchant referral revenue remaining to be recognized as of the most recent balance sheet date.

+ References

No definition available.

+ Details

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

- Definition

Divestiture related costs.

+ References

No definition available.

+ Details

Name:	wash_DivestitureCosts
Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Divestiture related costs after tax.

+ References

No definition available.

+ Details

Name:	wash_DivestitureCostsAfterTax
Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Earnings per share representing divestiture costs related to the sale of the merchant processing service business line.

+ References

No definition available.

+ Details

Name:	wash_DivestitureCostsEarningsPerShare
Namespace Prefix:	wash_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Earnings per share representing the gain recognized on the sale of the merchant processing service business line.

+ References

No definition available.

+ Details

Name:	wash_EarningsperShareonGainonSaleofBusinessLine
Namespace Prefix:	wash_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of gain recognized on the sale of the merchant service business line, after-taxes.

+ References

No definition available.

+ Details

Name:	wash_GainonSaleofBusinessLineAfterTaxAmount
Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of gain recognized in connection with the sale of the merchant processing service business line before income taxes.

+ References

No definition available.

+ Details

Name:	wash_GainonSaleofBusinessLineBeforeTaxAmount
Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period, excluding the portion taken into income, in the liability reflecting revenue yet to be earned for which cash was received as a receivable resulting from the sale of business line.

+ References

No definition available.

+ Details

Name:	wash_IncreaseDecreaseInDeferredRevenueFromSaleOfBusinessLine
Namespace Prefix:	wash_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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