Investments In Unconsolidated Joint Ventures (Summary Of The Results Of Financial Position) (Details) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]    
Rental property, net $ 138,806 $ 143,369
Loan receivable 41,610  
Other assets 75,536 71,920
Total assets 255,952 215,289
Mortgages, loans payable and other obligations 137,925 140,975
Other liabilities 8,313 6,884
Partners'/members' capital (deficit) 109,714 67,430
Total liabilities and partners'/members' capital (deficit) 255,952 215,289
Company's investments in unconsolidated joint ventures, net 65,559 32,015
Plaza VIII & IX Associates [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 7,875 8,335
Other assets 1,478 933
Total assets 9,353 9,268
Other liabilities 530 531
Partners'/members' capital (deficit) 8,823 8,737
Total liabilities and partners'/members' capital (deficit) 9,353 9,268
Company's investments in unconsolidated joint ventures, net 4,334 4,291
Harborside South Pier [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 56,265 59,733
Other assets 14,623 12,840
Total assets 70,888 72,573
Mortgages, loans payable and other obligations 69,405 70,690
Other liabilities 5,814 4,982
Partners'/members' capital (deficit) (4,331) (3,099)
Total liabilities and partners'/members' capital (deficit) 70,888 72,573
Company's investments in unconsolidated joint ventures, net (960) (343)
Red Bank Corporate Plaza [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 22,353 22,903
Other assets 3,301 2,909
Total assets 25,654 25,812
Mortgages, loans payable and other obligations 17,542 18,100
Other liabilities 309 117
Partners'/members' capital (deficit) 7,803 7,595
Total liabilities and partners'/members' capital (deficit) 25,654 25,812
Company's investments in unconsolidated joint ventures, net 3,804 3,676
Gramercy Agreement [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 38,267 39,276
Other assets 5,680 5,669
Total assets 43,947 44,945
Mortgages, loans payable and other obligations 50,978 50,978
Other liabilities 935 1,086
Partners'/members' capital (deficit) (7,966) (7,119)
Total liabilities and partners'/members' capital (deficit) 43,947 44,945
12 Vreeland [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 14,046 13,122
Other assets 1,356 521
Total assets 15,402 13,643
Mortgages, loans payable and other obligations   1,207
Other liabilities 725 168
Partners'/members' capital (deficit) 14,677 12,268
Total liabilities and partners'/members' capital (deficit) 15,402 13,643
Company's investments in unconsolidated joint ventures, net 10,837 10,233
Boston-Downtown Crossing [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 46,198 46,121
Total assets 46,198 46,121
Partners'/members' capital (deficit) 46,198 46,121
Total liabilities and partners'/members' capital (deficit) 46,198 46,121
Company's investments in unconsolidated joint ventures, net 13,006 13,005
Gale Jefferson [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 2,673 2,927
Total assets 2,673 2,927
Partners'/members' capital (deficit) 2,673 2,927
Total liabilities and partners'/members' capital (deficit) 2,673 2,927
Company's investments in unconsolidated joint ventures, net 1,068 1,153
Stamford SM LLC [Member]
    
Schedule of Equity Method Investments [Line Items]    
Loan receivable 41,610  
Other assets 227  
Total assets 41,837  
Partners'/members' capital (deficit) 41,837  
Total liabilities and partners'/members' capital (deficit) 41,837  
Company's investments in unconsolidated joint ventures, net $ 33,470