Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.1
Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details)
 1 Months Ended 3 Months Ended
Apr. 30, 2021
USD ($)
Mar. 31, 2021
USD ($)
property
Mar. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Fair value of Company's long-term debt   $ 2,844,003,000   $ 2,879,002,000
Principal balance outstanding   2,821,964,000   $ 2,801,797,000
Properties aggregate net book value   415,000,000.0    
Land and other impairments   $ 413,000 $ 5,263,000  
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   1    
Unrealized gains (losses) on real estate held for sale   $ 1,200,000    
Land and other impairments   400,000    
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Short Hills, New Jersey [Member]        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Gain (loss) on sale of property   $ 2,200,000    
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   11    
Number of disposal groups | property   4    
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    
Disposal Group, Not Discontinued Operations [Member]        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Unrealized gains (losses) on real estate held for sale   $ 1,020,000    
Gain (loss) on sale of property   21,761,000    
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   1,200,000    
Land and other impairments   $ 400,000    
Subsequent Event [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Short Hills, New Jersey [Member]        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Gain (loss) on sale of property $ 2,200,000