Share-Based Compensation Arrangements (Nonvested Performance Shares) (Details) (Performance Based Nonvested Shares [Member], USD $)	6 Months Ended
Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value	$ 34.66
Award Vesting Period	3 years
Performance share awards, shares vesting percentage	140.00%
Performance share awards, shares vesting	21,140
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Instruments Other than Options Minimum Shares Earned to Target Percentage	0.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Instruments Other than Options Maximum Shares Earned to Target Percentage	200.00%

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

The current assumption based on the most recent information available shares vesting percentage for performance nonvested equitybased awards.

+ References

No definition available.

+ Details

Name:	wash_ShareBasedCompensationArrangementByShareBasedAwardEquityInstrumentsOtherThanOptionsSharesVestingPercentage
Namespace Prefix:	wash_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percent of shares earned to the target of equity instruments other than options, the maximum percentage of the range.

+ References

No definition available.

+ Details

Name:	wash_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsSharesEarnedToTargetPercentageMaximum
Namespace Prefix:	wash_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percent of shares earned to the target for equity instruments other than options, the minimum percentage of the range.

+ References

No definition available.

+ Details

Name:	wash_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsSharesEarnedToTargetPercentageMinimum
Namespace Prefix:	wash_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Shares vesting for performance nonvested equity based awards based on the most recent information available.

+ References

No definition available.

+ Details

Name:	wash_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsSharesVesting
Namespace Prefix:	wash_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration