Annual report pursuant to Section 13 and 15(d)

Discontinued Operations (Narrative) (Details)

v3.19.3.a.u2
Discontinued Operations (Narrative) (Details)
 12 Months Ended
Dec. 31, 2019
USD ($)
ft²
item
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]  
Properties | item 21
Unrealized losses on disposition of rental property | $ $ (144,090,000)
Suburban Office Portfolio [Member]  
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]  
Area of real estate property held for sale (in square feet) | ft² 6,600,000
Suburban Office Properties [Member]  
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]  
Number of properties sold | item 2
Area of property sold (in square feet) | ft² 497,000
Number Of Buildings Held For Sale | item 35
Area of real estate property held for sale (in square feet) | ft² 6,100,000
Sales proceeds | $ $ 52,200,000