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Stock Based Compensation - Narrative (Details) (USD $)
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12 Months Ended | 0 Months Ended | 12 Months Ended | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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Feb. 17, 2011
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Feb. 17, 2011
Prior LTIP [Member]
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Dec. 31, 2011
Prior LTIP [Member]
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Dec. 31, 2013
Washington Real Estate Investment Trust 2007 Omnibus Long Term Incentive Plan [Member]
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Dec. 31, 2013
New STIP [Member]
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Dec. 31, 2013
New STIP [Member]
Performance-Based Awards [Member]
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Dec. 31, 2013
New STIP [Member]
Service-Based Awards [Member]
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Dec. 31, 2013
New LTIP [Member]
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Dec. 31, 2013
New LTIP [Member]
Minimum [Member]
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Dec. 31, 2013
New LTIP [Member]
Maximum [Member]
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Dec. 31, 2013
New LTIP [Member]
Unrestricted Share Units [Member]
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Dec. 31, 2013
New LTIP [Member]
Restricted Share Units [Member]
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Dec. 31, 2013
Unrestricted Share Awards [Member]
New LTIP [Member]
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Dec. 31, 2013
Cash [Member]
New STIP [Member]
Performance-Based Awards [Member]
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Dec. 31, 2013
Restricted Share Units [Member]
New STIP [Member]
Performance-Based Awards [Member]
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Dec. 31, 2013
Restricted Share Units [Member]
New STIP [Member]
Service-Based Awards [Member]
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Dec. 31, 2013
Restricted Share Units [Member]
New LTIP [Member]
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Dec. 31, 2013
Restricted Share Units [Member]
New LTIP [Member]
Performance-Based Awards [Member]
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Dec. 31, 2013
Management [Member]
Restricted Share Units [Member]
Prior LTIP [Member]
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Dec. 31, 2013
Chief Executive Officer [Member]
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Dec. 31, 2013
Officer [Member]
Restricted Share Units [Member]
Prior LTIP [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||||||||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost | $ 1,000,000 | |||||||||||||||||||||||
| Number of shares authorized | 2,000,000 | |||||||||||||||||||||||
| Plan in effect, period | 10 years | |||||||||||||||||||||||
| Percentage payable In unrestricted shares | 50.00% | 50.00% | ||||||||||||||||||||||
| Percentage payable in restricted shares | 65.00% | 150.00% | 50.00% | 50.00% | 50.00% | |||||||||||||||||||
| Percentage of awards earned | 15.00% | |||||||||||||||||||||||
| Award vesting period | 4 years | 3 years | 3 years | 3 years | 1 year | 5 years | 5 years | |||||||||||||||||
| Percentage officer may elect to defer | 80.00% | |||||||||||||||||||||||
| Percentage of employer contribution, restricted units | 25.00% | |||||||||||||||||||||||
| Total compensation cost not yet recognized, period for recognition | 3 years | 4 years | 3 years | 4 years | 6 years | 5 years | ||||||||||||||||||
| Percentage of restricted shares subject to performance conditions | 20.00% | |||||||||||||||||||||||
| Performance period | 1 year | 3 years | 1 year | 1 year | ||||||||||||||||||||
| Percentage of potential award dependent upon market condition | 40.00% | |||||||||||||||||||||||
| Percentage of potential award based upon strategic plan fulfillment | 60.00% | |||||||||||||||||||||||
| Weighting for performance measurement based on cumulative 3-Year total shareholder return | 50.00% | |||||||||||||||||||||||
| Weighting for performance measurement based on 20 peer comapnies | 50.00% | |||||||||||||||||||||||
| Fair value assumptions, expected volatility rate | 58.10% | |||||||||||||||||||||||
| Fair value assumptions, risk free interest rate | 1.20% | |||||||||||||||||||||||
| Fair value assumptions, expected term | 3 years | 4 years | ||||||||||||||||||||||
| Closing share price, date of grant | $ 30.91 | |||||||||||||||||||||||
| Grant date fair value as a percentage of base salary | 79.00% | 185.00% | ||||||||||||||||||||||
| Number of restricted shares subsequent to adoption of new share-based compensation plan | 154,400 | |||||||||||||||||||||||
| Other than options, nonvested, number, | 59,100 | |||||||||||||||||||||||
| Trustee share-based compensation | 55,000 | 55,000 | 55,000 | |||||||||||||||||||||
| Stock-based compensation expense | $ 6,246,000 | $ 5,856,000 | $ 5,597,000 | |||||||||||||||||||||