Investments In Unconsolidated Joint Ventures (Summary Of Unconsolidated Joint Ventures) (Details)
$ in Thousands
 1 Months Ended 3 Months Ended
Feb. 28, 2019
Oct. 31, 2019
USD ($)
Mar. 31, 2020
USD ($)
ft²
item
Mar. 31, 2019
USD ($)
Mar. 12, 2020
Dec. 31, 2019
USD ($)
Aug. 01, 2019
Jan. 31, 2019
Schedule of Equity Method Investments [Line Items]                
Carrying Value     $ 202,574     $ 209,091    
Purchase price of property     $ 62,992 $ 37,733        
Minimum [Member]                
Schedule of Equity Method Investments [Line Items]                
Company's Effective Ownership %     20.00%          
Maximum [Member]                
Schedule of Equity Method Investments [Line Items]                
Company's Effective Ownership %     85.00%          
Crystal House [Member]                
Schedule of Equity Method Investments [Line Items]                
Percentage of interest in developable land     50.00%          
Number of units available for development | item     738          
PI North - Riverwalk C [Member] | Construction Loan [Member]                
Schedule of Equity Method Investments [Line Items]                
Maximum borrowing capacity     $ 112,000          
Urby At Harborside [Member] | Construction/Permanent Loan [Member]                
Schedule of Equity Method Investments [Line Items]                
Company's Effective Ownership %     85.00%          
PI North - Land [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     836          
Residual ownership interest     20.00%          
12 Vreeland Road [Member]                
Schedule of Equity Method Investments [Line Items]                
Impairment charge     $ 3,700          
The Shops At 40 Park Property [Member] | Metropolitan At 40 Park [Member]                
Schedule of Equity Method Investments [Line Items]                
Rentable Square Feet (sf) | ft²     50,973          
Balance     $ 6,067          
Property Debt, Interest Rate, Spread Over LIBOR   2.25%            
Residual ownership interest     25.00%          
Mortgage loan, maturity month and year   October 2021 October 2019          
Lofts At 40 Park Property [Member] | Metropolitan At 40 Park [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     59          
Property Debt, Interest Rate, Spread Over LIBOR     2.25%          
Indirect ownership interest     50.00%          
Number of stories | item     5          
Lofts At 40 Park Property [Member] | Metropolitan At 40 Park [Member] | Construction Loan [Member]                
Schedule of Equity Method Investments [Line Items]                
Property Debt, Interest Rate, Spread Over LIBOR   1.50%            
Maximum borrowing capacity   $ 18,200            
Mortgage loan, maturity month and year   January 2023            
Metropolitan Property [Member] | Metropolitan At 40 Park [Member]                
Schedule of Equity Method Investments [Line Items]                
Balance     $ 34,943          
Property Debt, Interest Rate     3.25%          
Mortgage loan, maturity month and year     September 2020          
Unconsolidated Joint Venture Multi-Family Properties [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     2,611          
Unconsolidated Joint Venture Multi-Family Properties [Member] | Metropolitan At 40 Park [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     189          
Company's Effective Ownership %     25.00%          
Carrying Value     $ 4,368     7,257    
Balance     $ 59,210          
Unconsolidated Joint Venture Multi-Family Properties [Member] | RiverTrace At Port Imperial [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     316          
Company's Effective Ownership %     22.50%          
Carrying Value     $ 7,190     7,463    
Balance     $ 82,000          
Property Debt, Maturity Date     Nov. 10, 2026          
Property Debt, Interest Rate     3.21%          
Unconsolidated Joint Venture Multi-Family Properties [Member] | Crystal House [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     825          
Company's Effective Ownership %     25.00%          
Carrying Value     $ 28,662     28,823    
Balance     $ 158,635          
Property Debt, Maturity Date     Jun. 01, 2020          
Property Debt, Interest Rate     3.50%          
Unconsolidated Joint Venture Multi-Family Properties [Member] | PI North - Riverwalk C [Member]                
Schedule of Equity Method Investments [Line Items]                
Property Debt, Interest Rate     2.75%          
Unconsolidated Joint Venture Multi-Family Properties [Member] | Marbella II [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     360          
Company's Effective Ownership %     40.00%       24.27% 50.00%
Carrying Value     $ 35,653     35,527    
Balance     $ 41,773          
Property Debt, Maturity Date     Dec. 06, 2021          
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverpark At Harrison [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     141          
Company's Effective Ownership %     45.00%          
Carrying Value     $ 956     1,015    
Balance     $ 29,117          
Property Debt, Maturity Date     Aug. 01, 2025          
Property Debt, Interest Rate     3.70%          
Unconsolidated Joint Venture Multi-Family Properties [Member] | Station House [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     378          
Company's Effective Ownership %     50.00%          
Carrying Value     $ 35,209     35,676    
Balance     $ 96,438          
Property Debt, Maturity Date     Jul. 01, 2033          
Property Debt, Interest Rate     4.82%          
Unconsolidated Joint Venture Multi-Family Properties [Member] | Urby At Harborside [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     762          
Company's Effective Ownership %     85.00%          
Carrying Value     $ 78,532     79,790    
Balance     $ 192,000          
Property Debt, Maturity Date     Aug. 01, 2029          
Property Debt, Interest Rate     5.197%          
Unconsolidated Joint Venture Multi-Family Properties [Member] | PI North - Land [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     836          
Company's Effective Ownership %     20.00%          
Carrying Value     $ 1,678     1,678    
Unconsolidated Joint Venture Multi-Family Properties [Member] | Liberty Landing [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     850          
Company's Effective Ownership %     50.00%          
Carrying Value     $ 337     337    
Unconsolidated Joint Venture Multi-Family Properties [Member] | Hillsborough 206 [Member]                
Schedule of Equity Method Investments [Line Items]                
Rentable Square Feet (sf) | ft²     160,000          
Company's Effective Ownership %     50.00%          
Carrying Value     $ 1,962     1,962    
Unconsolidated Joint Venture Office Buildings [Member]                
Schedule of Equity Method Investments [Line Items]                
Rentable Square Feet (sf) | ft²     200,000          
Unconsolidated Joint Venture Office Buildings [Member] | Red Bank [Member]                
Schedule of Equity Method Investments [Line Items]                
Percentage of interest sold 50.00%              
Unconsolidated Joint Venture Office Buildings [Member] | 12 Vreeland Road [Member]                
Schedule of Equity Method Investments [Line Items]                
Rentable Square Feet (sf) | ft²     139,750          
Company's Effective Ownership %     50.00%          
Carrying Value     $ 3,957     3,846    
Balance     $ 5,850          
Property Debt, Maturity Date     Jul. 01, 2023          
Property Debt, Interest Rate     2.87%          
Unconsolidated Joint Venture Office Buildings [Member] | Offices At Crystal Lake [Member]                
Schedule of Equity Method Investments [Line Items]                
Rentable Square Feet (sf) | ft²     106,345          
Company's Effective Ownership %     31.25%          
Carrying Value     $ 3,541     3,521    
Balance     $ 3,128          
Property Debt, Maturity Date     Nov. 01, 2023          
Property Debt, Interest Rate     4.76%          
Unconsolidated Joint Venture Other Property [Member]                
Schedule of Equity Method Investments [Line Items]                
Carrying Value     $ 202,574     209,091    
Balance     $ 768,151          
Unconsolidated Joint Venture Other Property [Member] | Riverwalk Retail [Member]                
Schedule of Equity Method Investments [Line Items]                
Rentable Square Feet (sf) | ft²     30,745          
Company's Effective Ownership %     20.00%   80.00%      
Carrying Value           1,467    
Unconsolidated Joint Venture Other Property [Member] | Hyatt Regency Hotel Jersey City [Member]                
Schedule of Equity Method Investments [Line Items]                
Number of Apartment Units | item     351          
Company's Effective Ownership %     50.00%          
Carrying Value              
Balance     $ 100,000          
Property Debt, Maturity Date     Oct. 01, 2026          
Property Debt, Interest Rate     3.668%          
Unconsolidated Joint Venture Other Property [Member] | Other [Member]                
Schedule of Equity Method Investments [Line Items]                
Carrying Value     $ 529     $ 729