Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.1
Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details)
 3 Months Ended
Mar. 31, 2020
USD ($)
property
item
Dec. 31, 2019
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair value of Company's long-term debt $ 2,919,633,000 $ 2,791,629,000
Principal balance outstanding 2,877,121,000 $ 2,808,517,000
Unrealized losses on rental properties held for sale (7,915,000)  
Properties aggregate net book value 898,000,000  
Land and other Impairments 5,263,000  
Parsippany, Madison, Short Hills, Edison, Red Bank, and Florhan Park [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Unrealized losses on rental properties held for sale 53,000,000.0  
Land and other Impairments $ 5,300,000  
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Parsippany, Madison, Short Hills, Edison, Red Bank, and Florhan Park [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Number of properties held for sale | property 20  
Number of disposal groups | item 4  
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 34  
Number of disposal groups | property 12  
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 losses on rental properties held for sale $ (45,068,000)  
Discontinued Operations [Member] | Parsippany, Madison, Short Hills, Edison, Red Bank, and Florhan Park [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Unrealized losses on rental properties held for sale 45,100,000  
Land and other Impairments $ 5,300,000