Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation (Details)

v3.7.0.1
Stock Based Compensation (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation expense $ 1.1 $ 1.5
Restricted Share Awards    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Fair value of share grants vested $ 1.6 $ 2.0
Total unvested restricted share awards (in shares) 258,759  
Weighted average grant date fair value (in dollars per share) $ 30.13  
Total compensation costs, non-vested restricted share awards $ 5.8  
Total compensation cost not yet recognized, period for recognition (in months) 28 months  
Washington Real Estate Investment Trust 2016 Omnibus Long Term Incentive Plan [Domain]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock based plan, aggregate number of shares authorized (in shares) 2,400,000.0  
Stock based plan, period in effect (in years) 10 years