Quarterly report pursuant to Section 13 or 15(d)

Discontinued Operations (Narrative) (Details)

v3.20.1
Discontinued Operations (Narrative) (Details)
$ in Thousands
3 Months Ended 15 Months Ended
Mar. 31, 2020
USD ($)
ft²
property
item
Mar. 31, 2020
USD ($)
ft²
property
Dec. 19, 2019
ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Unrealized losses on disposition of rental property $ (45,068)    
Suburban Office Portfolio [Member]      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Area of property (in square feet) | ft²     6,600,000
Four Disposal Group [Member]      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Number of disposal groups | item 4    
Properties | property 19    
Unrealized losses on disposition of rental property $ 45,100    
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Suburban Office Portfolio [Member]      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Number of disposal groups | item 12    
Number of real estate properties | property 34 34  
Area of property (in square feet) | ft² 5,900,000 5,900,000  
Disposal Group, Not Discontinued Operations [Member]      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Number of properties sold | item 1    
Sales proceeds $ 35,065    
Disposal Group, Not Discontinued Operations [Member] | Properties Disposed One [Member] | Suburban Office Portfolio [Member]      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Number of properties sold | property   3  
Disposal Group, Not Discontinued Operations [Member] | Properties Disposed One [Member] | Suburban Office Properties [Member]      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Sales proceeds   $ 87,200  
Area of property (in square feet) | ft² 697,000 697,000  
Disposal Group, Not Discontinued Operations [Member] | Properties Disposed Two [Member]      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Sales proceeds $ 335,500    
Number of real estate properties | property 17 17  
Area of property (in square feet) | ft² 2,500,000 2,500,000