Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation - Narrative (Details)

v2.4.0.6
Stock Based Compensation - Narrative (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
12 Months Ended 0 Months Ended 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Feb. 17, 2011
Feb. 17, 2011
Prior LTIP [Member]
Dec. 31, 2010
Prior LTIP [Member]
Dec. 31, 2012
Washington Real Estate Investment Trust 2007 Omnibus Long Term Incentive Plan [Member]
Dec. 31, 2012
New STIP [Member]
Dec. 31, 2012
New STIP [Member]
Performance-Based Awards [Member]
Dec. 31, 2012
New STIP [Member]
Service-Based Awards [Member]
Dec. 31, 2012
New LTIP [Member]
Dec. 31, 2012
New LTIP [Member]
Minimum [Member]
Dec. 31, 2012
New LTIP [Member]
Maximum [Member]
Dec. 31, 2012
New LTIP [Member]
Unrestricted Share Units [Member]
Dec. 31, 2012
New LTIP [Member]
Restricted Share Units [Member]
Dec. 31, 2012
Unrestricted Share Awards [Member]
New LTIP [Member]
Dec. 31, 2012
Cash [Member]
New STIP [Member]
Performance-Based Awards [Member]
Dec. 31, 2012
Restricted Share Units [Member]
New STIP [Member]
Performance-Based Awards [Member]
Dec. 31, 2012
Restricted Share Units [Member]
New STIP [Member]
Service-Based Awards [Member]
Dec. 31, 2012
Restricted Share Units [Member]
New LTIP [Member]
Dec. 31, 2012
Restricted Share Units [Member]
New LTIP [Member]
Performance-Based Awards [Member]
Dec. 31, 2012
Management [Member]
Restricted Share Units [Member]
Prior LTIP [Member]
Dec. 31, 2012
Officer [Member]
Restricted Share Units [Member]
Prior LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                              
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  
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 $ 55 $ 55                                        
Stock-based compensation expense $ 5,856 $ 5,597 $ 5,852