Fair Value Measurements (Quantitative Information About Level 3 Assets Measured at Fair Value on a Recurring Basis) (Details) (Recurring [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
Jun. 30, 2013	Dec. 31, 2012
Fair Value Inputs Assets Quantitative Information [Line Items]
Mortgage loans held for sale	$ 28,889	$ 50,056
Level 3 [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Mortgage loans held for sale	0	9,813
Discounted Cash Flow [Member] \| Level 3 [Member] \| Forward Loan Commitments, Liabilities [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Derivative Liabilities		(186)
Discounted Cash Flow [Member] \| Level 3 [Member] \| Trust preferred securities: Collateralized debt obligations [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Securities available for sale	397	843
Discounted Cash Flow [Member] \| Level 3 [Member] \| Mortgage loans held for sale [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Mortgage loans held for sale		9,813
Discounted Cash Flow [Member] \| Level 3 [Member] \| Forward Loan Commitments, Assets [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Derivative Assets		$ 44
Range of Inputs: Minimum [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Forward Loan Commitments, Liabilities [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		3.25%
Credit Risk Adjustment		0.25%
Range of Inputs: Minimum [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Trust preferred securities: Collateralized debt obligations [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Discount Rate	16.50%	16.75%
Cummulative Default Percentage	3.00%	3.30%
Loss Given Default Percentage	85.00%	85.00%
Range of Inputs: Minimum [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Mortgage loans held for sale [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		2.875%
Credit Risk Adjustment		0.25%
Range of Inputs: Minimum [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Forward Loan Commitments, Assets [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		3.25%
Credit Risk Adjustment		0.25%
Range of Inputs: Maximum [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Forward Loan Commitments, Liabilities [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		3.875%
Credit Risk Adjustment		0.25%
Range of Inputs: Maximum [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Trust preferred securities: Collateralized debt obligations [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Discount Rate	16.50%	16.75%
Cummulative Default Percentage	100.00%	100.00%
Loss Given Default Percentage	100.00%	100.00%
Range of Inputs: Maximum [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Mortgage loans held for sale [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		4.95%
Credit Risk Adjustment		0.25%
Range of Inputs: Maximum [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Forward Loan Commitments, Assets [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		3.875%
Credit Risk Adjustment		0.25%
Weighted Average [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Forward Loan Commitments, Liabilities [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		3.69%
Credit Risk Adjustment		0.25%
Weighted Average [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Trust preferred securities: Collateralized debt obligations [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Discount Rate	16.50%	16.75%
Cummulative Default Percentage	19.10%	25.70%
Loss Given Default Percentage	91.00%	90.90%
Weighted Average [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Mortgage loans held for sale [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		3.71%
Credit Risk Adjustment		0.25%
Weighted Average [Member] \| Discounted Cash Flow [Member] \| Level 3 [Member] \| Forward Loan Commitments, Assets [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Interest Rate		3.56%
Credit Risk Adjustment		0.25%

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

+ Details

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

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13495-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FIN39-1

-Paragraph 10A, 10B

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 4, 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References

+ Details

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

- Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Risk associated with risk of default, credit spread risk and downgrade risk, expressed as a percentage, used as an input to measure fair value.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

+ References

No definition available.

+ Details

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

- Definition

The cummulative default percentage represents the lifetime defaults assumed, excluding currently defaulted collateral and including all performing and currently deferring collateral. As a result, the cummulative default percentage also reflects assumptions of the possibility of currently deferring collateral curing and becoming current.

+ References

No definition available.

+ Details

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

- Definition

The entities interest rate used to when quoted market prices were not available.

+ References

No definition available.

+ Details

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

- Definition

The loss given default percentage represents the percentage of current and projected defaults assumed to be lost.

+ References

No definition available.

+ Details

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