Quarterly report pursuant to Section 13 or 15(d)

Mortgages, Loans Payable And Other Obligations (Summary Of Mortgages, Loans Payable And Other Obligations) (Details)

v3.10.0.1
Mortgages, Loans Payable And Other Obligations (Summary Of Mortgages, Loans Payable And Other Obligations) (Details)
9 Months Ended
Mar. 29, 2018
USD ($)
Mar. 01, 2018
USD ($)
Jan. 08, 2018
USD ($)
Sep. 30, 2018
USD ($)
property
item
Sep. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
Debt Instrument [Line Items]            
Principal balance outstanding       $ 2,807,718,000   $ 2,809,568,000
Borrowings from revolving credit facility       428,000,000 $ 428,000,000  
Payment for borrowings       381,000,000 $ 714,000,000  
Secured Debt [Member]            
Debt Instrument [Line Items]            
Principal balance outstanding       1,374,792,000   1,426,111,000
Unamortized deferred financing costs       (7,409,000)   (7,976,000)
Total mortgages, loans payable and other obligations, net       $ 1,367,383,000   1,418,135,000
Secured Debt [Member] | Harborside Plaza 5 [Member]            
Debt Instrument [Line Items]            
Property Name       Harborside Plaza 5    
Lender       The Northwestern Mutual Life Insurance Co. & New York Life Insurance Co.    
Effective rate       6.84%    
Principal balance outstanding         209,257,000
Payment for borrowings     $ 8,400,000      
Secured Debt [Member] | 23 Main Street [Member]            
Debt Instrument [Line Items]            
Property Name       23 Main Street    
Lender       Berkadia CMBS    
Effective rate       5.59%    
Principal balance outstanding         27,090,000
Payment for borrowings   $ 100,000        
Secured Debt [Member] | One River Center [Member]            
Debt Instrument [Line Items]            
Property Name       One River Center    
Lender       Guardian Life Insurance Co.    
Effective rate       7.31%    
Principal balance outstanding         40,485,000
Number of properties used to collateralized mortgage | property       3    
Payment for borrowings $ 1,800,000          
Secured Debt [Member] | Park Square [Member]            
Debt Instrument [Line Items]            
Property Name       Park Square    
Lender       Wells Fargo Bank N.A.    
LIBOR       LIBOR+1.87    
Spread over LIBOR       1.87%    
Principal balance outstanding       $ 25,517,000   26,567,000
Loan maturity date       Apr. 10, 2019    
Secured Debt [Member] | 250 Johnson Road [Member]            
Debt Instrument [Line Items]            
Property Name       250 Johnson    
Lender       M&T Bank    
LIBOR       LIBOR+2.35    
Spread over LIBOR       2.35%    
Principal balance outstanding       $ 41,768,000   32,491,000
Loan maturity date       May 20, 2019    
Secured Debt [Member] | 250 Johnson Road [Member] | Construction Loan [Member]            
Debt Instrument [Line Items]            
Maximum borrowing capacity       $ 42,000,000    
Loan extension period       1 year    
Extension fee       0.25%    
Secured Debt [Member] | Portside 5/6 [Member]            
Debt Instrument [Line Items]            
Property Name       Portside 5/6    
Lender       Citizens Bank    
LIBOR       LIBOR+2.50    
Spread over LIBOR       2.50%    
Principal balance outstanding       $ 69,787,000   45,778,000
Loan maturity date       Sep. 29, 2019    
Secured Debt [Member] | Portside 5/6 [Member] | Construction Loan [Member]            
Debt Instrument [Line Items]            
Maximum borrowing capacity       $ 73,000,000    
Number of extension options | item       2    
Loan extension period       1 year    
Extension fee       0.15%    
Secured Debt [Member] | Port Imperial 4/5 Hotel [Member]            
Debt Instrument [Line Items]            
Property Name       Port Imperial 4/5 Hotel    
Lender       Fifth Third Bank & Santander    
LIBOR       LIBOR+4.50    
Spread over LIBOR       4.50%    
Principal balance outstanding       $ 68,928,000   43,674,000
Loan maturity date       Oct. 06, 2019    
Secured Debt [Member] | Port Imperial 4/5 Hotel [Member] | Construction Loan [Member]            
Debt Instrument [Line Items]            
Maximum borrowing capacity       $ 94,000,000    
Number of extension options | item       2    
Loan extension period       1 year    
Extension fee       0.20%    
Secured Debt [Member] | Port Imperial South 11 [Member]            
Debt Instrument [Line Items]            
Property Name       Port Imperial South 11    
Lender       JPMorgan Chase    
LIBOR       LIBOR+2.35    
Spread over LIBOR       2.35%    
Principal balance outstanding       $ 67,427,000   46,113,000
Loan maturity date       Nov. 24, 2019    
Secured Debt [Member] | Port Imperial South 11 [Member] | Construction Loan [Member]            
Debt Instrument [Line Items]            
Maximum borrowing capacity       $ 78,000,000    
Number of extension options | item       2    
Loan extension period       1 year    
Extension fee       0.15%    
Secured Debt [Member] | Worcester [Member]            
Debt Instrument [Line Items]            
Property Name       Worcester    
Lender       Citizens Bank    
LIBOR       LIBOR+2.50    
Spread over LIBOR       2.50%    
Principal balance outstanding       $ 54,743,000   37,821,000
Loan maturity date       Dec. 10, 2019    
Secured Debt [Member] | Worcester [Member] | Construction Loan [Member]            
Debt Instrument [Line Items]            
Maximum borrowing capacity       $ 58,000,000    
Number of extension options | item       2    
Loan extension period       1 year    
Extension fee       0.15%    
Secured Debt [Member] | Monaco [Member]            
Debt Instrument [Line Items]            
Property Name       Monaco    
Lender       The Northwestern Mutual Life Insurance Co.    
Effective rate       3.15%    
Principal balance outstanding       $ 168,774,000   169,987,000
Loan maturity date       Feb. 01, 2021    
Adjustment for unamortized debt discount       $ 3,800,000    
Secured Debt [Member] | Port Imperial South 4/5 Retail [Member]            
Debt Instrument [Line Items]            
Property Name       Port Imperial South 4/5 Retail    
Lender       American General Life & A/G PC    
Effective rate       4.56%    
Principal balance outstanding       $ 4,000,000   4,000,000
Loan maturity date       Dec. 01, 2021    
Secured Debt [Member] | Portside 7 [Member]            
Debt Instrument [Line Items]            
Property Name       Portside 7    
Lender       CBRE Capital Markets/FreddieMac    
Effective rate       3.57%    
Principal balance outstanding       $ 58,998,000   58,998,000
Loan maturity date       Aug. 01, 2023    
Secured Debt [Member] | Alterra I & II [Member]            
Debt Instrument [Line Items]            
Property Name       Alterra I & II    
Lender       Capital One/FreddieMac    
Effective rate       3.85%    
Principal balance outstanding       $ 100,000,000   100,000,000
Loan maturity date       Feb. 01, 2024    
Secured Debt [Member] | The Chase At Overlook Ridge [Member]            
Debt Instrument [Line Items]            
Property Name       The Chase at Overlook Ridge    
Lender       New York Community Bank    
Effective rate       3.74%    
Principal balance outstanding       $ 135,750,000   135,750,000
Loan maturity date       Jan. 01, 2025    
Secured Debt [Member] | Marbella [Member]            
Debt Instrument [Line Items]            
Property Name       Marbella    
Lender       New York Life Insurance Company    
Effective rate       4.17%    
Principal balance outstanding       $ 131,000,000    
Loan maturity date       Aug. 10, 2026    
Secured Debt [Member] | 101 Hudson Street [Member]            
Debt Instrument [Line Items]            
Property Name       101 Hudson    
Lender       Wells Fargo CMBS    
Effective rate       3.20%    
Principal balance outstanding       $ 250,000,000   250,000,000
Loan maturity date       Oct. 11, 2026    
Secured Debt [Member] | Short Hills Portfolio [Member]            
Debt Instrument [Line Items]            
Property Name       Short Hills Portfolio    
Lender       Wells Fargo CMBS    
Effective rate       4.15%    
Principal balance outstanding       $ 124,500,000   124,500,000
Loan maturity date       Apr. 01, 2027    
Secured Debt [Member] | 150 Main St [Member]            
Debt Instrument [Line Items]            
Property Name       150 Main St.    
Lender       Natixis Real Estate Capital LLC    
Effective rate       4.48%    
Principal balance outstanding       $ 41,000,000   41,000,000
Loan maturity date       Aug. 05, 2027    
Secured Debt [Member] | Port Imperial 4/5 Garage Development [Member]            
Debt Instrument [Line Items]            
Property Name       Port Imperial South 4/5 Garage    
Lender       American General Life & A/G PC    
Effective rate       4.85%    
Principal balance outstanding       $ 32,600,000   $ 32,600,000
Loan maturity date       Dec. 01, 2029