Investments In Unconsolidated Joint Ventures (Summary Of The Results Of Financial Position) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2011
Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]    
Rental property, net $ 143,369 $ 152,372
Other assets 72,084 76,041
Total assets 215,453 228,413
Mortgages, loans payable and other obligations 140,975 146,731
Other liabilities 6,924 7,305
Partners'/members' capital (deficit) 67,554 74,377
Total liabilities and partners'/members' capital (deficit) 215,453 228,413
Company's investment in unconsolidated joint ventures, net 32,015 34,220
Plaza VIII & IX Associates [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 8,335 8,947
Other assets 933 906
Total assets 9,268 9,853
Other liabilities 531 529
Partners'/members' capital (deficit) 8,737 9,324
Total liabilities and partners'/members' capital (deficit) 9,268 9,853
Company's investment in unconsolidated joint ventures, net 4,291 4,584
Harborside South Pier [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 59,733 64,964
Other assets 12,840 11,681
Total assets 72,573 76,645
Mortgages, loans payable and other obligations 70,690 72,168
Other liabilities 4,982 4,356
Partners'/members' capital (deficit) (3,099) 121
Total liabilities and partners'/members' capital (deficit) 72,573 76,645
Company's investment in unconsolidated joint ventures, net (343) 1,161
Red Bank Corporate Plaza [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 22,903 23,594
Other assets 2,909 6,422
Total assets 25,812 30,016
Mortgages, loans payable and other obligations 18,100 20,424
Other liabilities 117 89
Partners'/members' capital (deficit) 7,595 9,503
Total liabilities and partners'/members' capital (deficit) 25,812 30,016
Company's investment in unconsolidated joint ventures, net 3,676 4,598
Gramercy Agreement [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 39,276 40,786
Other assets 5,669 6,261
Total assets 44,945 47,047
Mortgages, loans payable and other obligations 50,978 50,978
Other liabilities 1,086 1,719
Partners'/members' capital (deficit) (7,119) (5,650)
Total liabilities and partners'/members' capital (deficit) 44,945 47,047
Princeton Forrestal Village [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 160 1,435
Total assets 160 1,435
Other liabilities 40 612
Partners'/members' capital (deficit) 120 823
Total liabilities and partners'/members' capital (deficit) 160 1,435
Gale Kimball [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 4 51
Total assets 4 51
Partners'/members' capital (deficit) 4 51
Total liabilities and partners'/members' capital (deficit) 4 51
12 Vreeland [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 13,122 14,081
Other assets 521 734
Total assets 13,643 14,815
Mortgages, loans payable and other obligations 1,207 3,161
Other liabilities 168  
Partners'/members' capital (deficit) 12,268 11,654
Total liabilities and partners'/members' capital (deficit) 13,643 14,815
Company's investment in unconsolidated joint ventures, net 10,233 9,860
Boston-Downtown Crossing [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 46,121 46,111
Total assets 46,121 46,111
Partners'/members' capital (deficit) 46,121 46,111
Total liabilities and partners'/members' capital (deficit) 46,121 46,111
Company's investment in unconsolidated joint ventures, net 13,005 13,022
Gale Jefferson [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 2,927 2,440
Total assets 2,927 2,440
Partners'/members' capital (deficit) 2,927 2,440
Total liabilities and partners'/members' capital (deficit) 2,927 2,440
Company's investment in unconsolidated joint ventures, net $ 1,153 $ 995