Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.2
Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details)
 3 Months Ended 6 Months Ended
Jun. 30, 2021
USD ($)
property
Jun. 30, 2020
USD ($)
Jun. 30, 2021
USD ($)
property
Jun. 30, 2020
USD ($)
Dec. 31, 2020
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Fair value of Company's long-term debt $ 2,379,285,000   $ 2,379,285,000   $ 2,879,002,000
Principal balance outstanding 2,359,284,000   2,359,284,000   $ 2,801,797,000
Unrealized gains (losses) on real estate held for sale     (485,000)    
Properties aggregate net book value     84,800,000    
Land and other impairments 7,519,000 $ 16,846,000 7,932,000 $ 22,109,000  
Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Unrealized gains (losses) on real estate held for sale 1,400,000   $ 2,600,000    
Land Parcels [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Land and other impairments $ 7,500,000        
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 3   3    
Unrealized gains (losses) on real estate held for sale $ 1,400,000   $ 2,600,000    
Land and other impairments     $ 400,000    
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Number of properties held for sale | property 2   2    
Number of disposal groups | property     2    
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Retail Property [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Number of properties held for sale | property 1   1    
Disposal Group, Not Discontinued Operations [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Unrealized gains (losses) on real estate held for sale     $ (2,130,000)    
Gain (loss) on sale of property     26,991,000    
Disposal Group, Not Discontinued Operations [Member] | Hoboken, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Property impairments     6,000,000.0    
Disposal Group, Not Discontinued Operations [Member] | Land Parcels [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Land and other impairments $ 7,500,000   7,500,000    
Discontinued Operations [Member] | Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member]          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Unrealized gains (losses) on real estate held for sale 1,000,000.0   $ 2,100,000    
Land and other impairments $ 400,000