Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation (Details)

v2.4.0.6
Stock Based Compensation (Details) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation expense $ 1.0 $ 1.4
Restricted Share Awards [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share grants awarded (in shares) 102,641  
Share grants awarded at weighted average grant date fair $ 26.98  
Fair value of share grants vested 0.5 0.3
Total unvested restricted share awards (in shares) 233,378  
Weighted average grant date fair value (in dollars per share) $ 27.27  
Total compensation costs, non-vested restricted share awards $ 3.6  
Total compensation cost not yet recognized, period for recognition (in months) 15 months  
Washington Real Estate Investment Trust 2007 Omnibus Long-Term Incentive Plan [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock based plan, aggregate number of shares authorized (in shares) 2,000,000  
Stock based plan, period in effect (in years) 10 years