Annual report pursuant to Section 13 and 15(d)

Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details)

v3.20.4
Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details)
1 Months Ended 9 Months Ended 12 Months Ended
Mar. 31, 2020
property
Sep. 30, 2020
USD ($)
Dec. 31, 2020
USD ($)
property
item
Dec. 31, 2019
USD ($)
property
item
Dec. 31, 2018
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Fair value of Company's long-term debt     $ 2,879,002,000 $ 2,791,629,000  
Principal balance outstanding     2,801,797,000 2,808,518,000  
Land and other impairments     16,817,000 $ 32,444,000 $ 24,566,000
Property impairments   $ 36,600,000 36,582,000    
Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Unrealized losses on rental properties held for sale     $ (15,700,000)    
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Properties | property     6    
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Number of properties held for sale | property     6    
Number of disposal groups | item     3 6  
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member] | Fort Lee, Newark, Paramus, Bridgewater, Morris Plains And Rahway, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Number of properties held for sale | property       35  
Number of properties not expected to recover from estimated net sales proceeds | property       20  
Unrealized losses on rental properties held for sale       $ 164,400,000  
Properties aggregate net book value       966,000,000  
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member] | Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Number of properties held for sale | property     16    
Number of properties not expected to recover from estimated net sales proceeds | property     6    
Unrealized losses on rental properties held for sale     $ (15,700,000)    
Properties aggregate net book value     657,000,000    
Land and other impairments     $ 9,500,000    
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Hotel [Member] | Weehawken, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Property impairments   $ 36,600,000      
Properties | property     2    
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Land Parcels [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Land and other impairments     $ 7,300,000    
Properties | property     3    
Disposal Group, Not Discontinued Operations [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Unrealized losses on rental properties held for sale     $ (1,682,000) (39,049,000)  
Disposal Group, Not Discontinued Operations [Member] | Hotel [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Number of properties closed | property 1        
Disposal Group, Not Discontinued Operations [Member] | Hotel [Member] | Weehawken, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Properties | property     2    
Number of properties closed | property 1        
Discontinued Operations [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Unrealized losses on rental properties held for sale     $ (14,040,000) $ (135,052,000)  
Discontinued Operations [Member] | Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Unrealized losses on rental properties held for sale     (14,000,000)    
Land and other impairments     $ 9,500,000