Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation (Narrative) (Details)

v2.4.0.6
Stock Based Compensation (Narrative) (Details) (USD $)
12 Months Ended 12 Months Ended 12 Months Ended 0 Months Ended 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Feb. 17, 2011
Dec. 31, 2011
New LTIP [Member]
Y
Dec. 31, 2010
New LTIP [Member]
Dec. 31, 2011
Washington Real Estate Investment Trust 2007 Omnibus Long-Term Incentive Plan [Member]
years
Dec. 31, 2011
New STIP [Member]
Y
Dec. 31, 2011
New STIP [Member]
Performance-Based Awards [Member]
Dec. 31, 2011
New STIP [Member]
Service-Based Awards [Member]
Dec. 31, 2011
New STIP [Member]
Cash [Member]
Performance-Based Awards [Member]
Dec. 31, 2011
New STIP [Member]
Restricted Share Units [Member]
Performance-Based Awards [Member]
Dec. 31, 2011
New STIP [Member]
Restricted Share Units [Member]
Service-Based Awards [Member]
Dec. 31, 2011
New LTIP [Member]
Y
Dec. 31, 2011
New LTIP [Member]
Minimum [Member]
Dec. 31, 2011
New LTIP [Member]
Maximum [Member]
Dec. 31, 2011
New LTIP [Member]
Unrestricted Share Units [Member]
Dec. 31, 2011
New LTIP [Member]
Restricted Share Units [Member]
Dec. 31, 2011
New LTIP [Member]
Restricted Share Units [Member]
Dec. 31, 2011
New LTIP [Member]
Restricted Share Units [Member]
Performance-Based Awards [Member]
Y
Dec. 31, 2011
New LTIP [Member]
Unrestricted Share Awards [Member]
Y
Feb. 17, 2011
Prior LTIP [Member]
Dec. 31, 2010
Prior LTIP [Member]
Dec. 31, 2011
Prior LTIP [Member]
Restricted Share Units [Member]
Officer [Member]
Y
Dec. 31, 2010
Prior LTIP [Member]
Restricted Share Units [Member]
Officer [Member]
Dec. 31, 2011
Management [Member]
Prior LTIP [Member]
Restricted Share Units [Member]
Y
Dec. 31, 2010
Management [Member]
Prior LTIP [Member]
Restricted Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                                      
Stock based plan, aggregate number of shares authorized             2,000,000                                        
Stock based plan, period in effect (in years)             10                                        
Expected volatility 58.10%                                                    
Risk Free Interest Rate 1.20%                                                    
Closing Share Price, Date of Grant       $ 30.91                                              
Percentage Of Awards Earned                       50.00%     65.00% 150.00% 50.00% 50.00%                  
Percentage of Base Salary Used to Determine Grant Date Fair Value                             79.00% 185.00%                      
Expected life (from grant date)         3 4                                          
Share Based Compensation Arrangement By Share Based Payment Award Award Performance Period               1           3                       1  
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition         4         3                   4 3     5   6  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period               4 3 3                 1                
Percentage Payable In Unrestricted Shares                     50.00%             50.00%                  
Percentage of Awards Earned                         15.00%                            
Percentage Of Cash Portion Related To Deferred Compensation Plan               80.00%                                      
Percentage Of Potential Award Depend 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%                          
Percentage Of Deferred Amounts In Restricted Cash               25.00%                                      
Percentage Of Restricted Shares Subject To Performance Conditions               20.00%                                      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period, Maximum           3                                     5   5
Number of Restricted Shares Subsequent to Adoption of New share-based Compensation Plan                                           154,400          
Number of Restricted Shares Previously Granted and Nonvested                                             59,100        
Trustee Share-based Compensation $ 55,000 $ 55,000 $ 55,000                                                
Stock-based compensation expense $ 5,600,000 $ 5,900,000 $ 3,500,000