Annual report pursuant to Section 13 and 15(d)

Recent Transactions (Real Estate Held For Sale/Discontinued Operations/Dispositions) (Narrative) (Details)

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Recent Transactions (Real Estate Held For Sale/Discontinued Operations/Dispositions) (Narrative) (Details)
$ in Thousands
 1 Months Ended 12 Months Ended 27 Months Ended
Jan. 31, 2022
USD ($)
Dec. 31, 2021
USD ($)
ft²
property
Dec. 31, 2020
USD ($)
ft²
property
item
Dec. 31, 2019
USD ($)
Dec. 31, 2021
USD ($)
ft²
property
Dec. 19, 2019
ft²
Real Estate Properties [Line Items]            
Area of property (in square feet) | ft²   3,049,313 2,725,639   3,049,313  
Land and other impairments, net   $ 23,719 $ 16,817 $ 32,444    
Proceeds from the sale of property   52,391 64,947 825,613    
Book value   4,076,866 4,638,643   $ 4,076,866  
Less - accumulated depreciation and amortization   583,416 656,331   $ 583,416  
Impairment Of Land And Other   $ 23,719 $ 16,817 $ 32,444    
Suburban Office Portfolio [Member]            
Real Estate Properties [Line Items]            
Area of property (in square feet) | ft²           6,600,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Suburban Office Portfolio [Member]            
Real Estate Properties [Line Items]            
Area of property (in square feet) | ft²   6,300,000     6,300,000  
Gain (loss) on sale of property         $ 1,000  
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Subsequent Event [Member]            
Real Estate Properties [Line Items]            
Proceeds from the sale of property $ 210,000          
Repayment of debt $ 150,000          
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member]            
Real Estate Properties [Line Items]            
Number of real estate properties | property     16      
Area of property (in square feet) | ft²     3,000,000.0      
Number of disposal groups | item     6      
Disposal Group, Not Discontinued Operations [Member]            
Real Estate Properties [Line Items]            
Unrealized gains (losses) on real estate held for sale     $ (1,682)      
Discontinued Operations [Member]            
Real Estate Properties [Line Items]            
Unrealized gains (losses) on real estate held for sale   $ 3,700 (14,040)      
Gain (loss) on sale of property     $ 25,241      
Land and other impairments, net   10,200        
Impairment Of Land And Other   10,200        
Disposal Group, Held-for-sale, Under Contract [Member] | Suburban Office Portfolio [Member]            
Real Estate Properties [Line Items]            
Number of real estate properties | property     15      
Area of property (in square feet) | ft²     2,800,000      
Gain (loss) on sale of property     $ 652,400      
Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]            
Real Estate Properties [Line Items]            
Unrealized gains (losses) on real estate held for sale     $ (15,700)      
Number of properties not expected to recover from estimated net sales proceeds | property     6      
Land and other impairments, net     $ 9,500      
Number of disposal groups | item     3      
Less - accumulated depreciation and amortization     $ 169,031      
Impairment Of Land And Other     9,500      
Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Suburban Office Portfolio [Member]            
Real Estate Properties [Line Items]            
Less - accumulated depreciation and amortization     $ 161,040      
Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member]            
Real Estate Properties [Line Items]            
Number of real estate properties | property     16      
Unrealized gains (losses) on real estate held for sale     $ (15,700)      
Number of properties not expected to recover from estimated net sales proceeds | property     6      
Land and other impairments, net     $ 9,500      
Impairment Of Land And Other     9,500      
Parsippany, Madison, Short Hills, Edison, And Red Bank, New Jersey [Member] | Discontinued Operations [Member]            
Real Estate Properties [Line Items]            
Unrealized gains (losses) on real estate held for sale     $ 14,000      
Hoboken, New Jersey [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]            
Real Estate Properties [Line Items]            
Net proceeds   575,000        
Repayment of debt   400,000        
Payment for Debt Extinguishment or Debt Prepayment Cost   $ 20,000        
Parsippany, New Jersey [Member] | Discontinued Operations [Member]            
Real Estate Properties [Line Items]            
Number of real estate properties | property     2      
Book value     $ 11,300      
Holmdel, New Jersey [Member] | Discontinued Operations [Member] | Suburban Office Portfolio [Member]            
Real Estate Properties [Line Items]            
Area of property (in square feet) | ft²     350,000      
Book value     $ 19,800      
Less - accumulated depreciation and amortization     10,500      
Reversal of valuation allowance     $ 2,800      
Fort Lee, Parsippany, Madison, Short Hills, Edison, Red Bank, Florham Park [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Office [Member]            
Real Estate Properties [Line Items]            
Number of disposal groups | item     6      
Jersey City And Hoboken [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]            
Real Estate Properties [Line Items]            
Number of real estate properties | property   2     2  
Area of property (in square feet) | ft²   1,800,000     1,800,000