Annual report pursuant to Section 13 and 15(d)

Nature of Business - Properties Sold (Details)

v3.19.3.a.u2
Nature of Business - Properties Sold (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 19, 2019
Aug. 27, 2019
Aug. 21, 2019
Jul. 23, 2019
Jun. 26, 2019
Jun. 28, 2018
Jan. 19, 2018
Oct. 23, 2017
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Properties Sold [Line Items]                              
(Loss) gain on sale                   $ 339,000     $ 339,024 $ 0 $ 0
(Loss) gain on sale                 $ 61,000   $ (1,000) $ 2,500 59,961 2,495 24,915
2019 Properties                              
Properties Sold [Line Items]                              
(Loss) gain on sale                         398,985    
2019 Properties | Disposal group, not discontinued operations                              
Properties Sold [Line Items]                              
(Loss) gain on sale                         $ 398,985    
2019 Properties | Disposal group, not discontinued operations | Quantico Corporate Center | Office                              
Properties Sold [Line Items]                              
(Loss) gain on sale         $ (1,046)                    
2019 Properties | Disposal group, not discontinued operations | Shopping Center Portfolio                              
Properties Sold [Line Items]                              
(Loss) gain on sale       $ 333,000                      
2019 Properties | Disposal group, not discontinued operations | Frederick Crossing and Frederick County Square                              
Properties Sold [Line Items]                              
(Loss) gain on sale     $ 9,500                        
2019 Properties | Disposal group, not discontinued operations | Centre at Hagerstown                              
Properties Sold [Line Items]                              
(Loss) gain on sale   $ 3,500                          
2019 Properties | Disposal group, not discontinued operations | 1776 G Street | Office                              
Properties Sold [Line Items]                              
(Loss) gain on sale $ 61,007                            
2019 Properties | Discontinued operations | Shopping Center Portfolio | Retail                              
Properties Sold [Line Items]                              
(Loss) gain on sale       $ 333,023                      
2019 Properties | Discontinued operations | Frederick Crossing and Frederick County Square | Retail                              
Properties Sold [Line Items]                              
(Loss) gain on sale     $ 9,507                        
2019 Properties | Discontinued operations | Centre at Hagerstown | Retail                              
Properties Sold [Line Items]                              
(Loss) gain on sale   $ (3,506)                          
2018 Properties                              
Properties Sold [Line Items]                              
(Loss) gain on sale                           2,495  
2018 Properties | Disposal group, not discontinued operations                              
Properties Sold [Line Items]                              
(Loss) gain on sale                           $ 2,495  
2018 Properties | Disposal group, not discontinued operations | Braddock Metro Center | Office                              
Properties Sold [Line Items]                              
(Loss) gain on sale             $ 0                
2018 Properties | Disposal group, not discontinued operations | 2445 M Street | Office                              
Properties Sold [Line Items]                              
(Loss) gain on sale           $ 2,495                  
2017 Properties                              
Properties Sold [Line Items]                              
(Loss) gain on sale                             23,838
2017 Properties | Disposal group, not discontinued operations                              
Properties Sold [Line Items]                              
(Loss) gain on sale                             23,838
2017 Properties | Disposal group, not discontinued operations | Walker House Apartments | Multifamily                              
Properties Sold [Line Items]                              
(Loss) gain on sale               $ 23,838             $ 23,800