Annual report pursuant to Section 13 and 15(d)

Recent Transactions (Unconsolidated Joint Venture Activity) (Narrative) (Details)

v3.20.4
Recent Transactions (Unconsolidated Joint Venture Activity) (Narrative) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 17, 2020
Feb. 28, 2019
Dec. 31, 2020
Dec. 31, 2019
Real Estate Properties [Line Items]        
Gain on sale from unconsolidated joint ventures     $ 35,184 $ 903
Red Bank [Member] | Unconsolidated Joint Venture Office Buildings [Member]        
Real Estate Properties [Line Items]        
Gain on sale   $ 900    
Sale price   $ 4,200    
Crystal House [Member]        
Real Estate Properties [Line Items]        
Gain on sale     35,100  
Crystal House [Member] | Unconsolidated Joint Venture Office Buildings [Member]        
Real Estate Properties [Line Items]        
Gain on sale from unconsolidated joint ventures     376,600  
Gain on sale     35,100  
Gain (loss) on sale of property     $ 62,700  
Hillsborough 206 [Member]        
Real Estate Properties [Line Items]        
Gain on sale $ 100      
Sale price 2,100      
Hillsborough 206 [Member] | Unconsolidated Joint Venture Developable Land [Member]        
Real Estate Properties [Line Items]        
Gain on sale 100      
Sale price $ 2,100