Investments In Unconsolidated Joint Ventures (Summary Of The Results Of Financial Position) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2012
Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]    
Rental property, net $ 142,588 $ 143,369
Other assets 113,060 71,920
Total assets 255,648 215,289
Mortgages, loans payable and other obligations 139,955 140,975
Other liabilities 8,269 6,884
Partners'/members' capital (deficit) 107,424 67,430
Total liabilities and partners'/members' capital (deficit) 255,648 215,289
Company's investments in unconsolidated joint ventures, net 63,799 32,015
Plaza VIII & IX Associates [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 8,182 8,335
Other assets 1,108 933
Total assets 9,290 9,268
Other liabilities 532 531
Partners'/members' capital (deficit) 8,758 8,737
Total liabilities and partners'/members' capital (deficit) 9,290 9,268
Company's investments in unconsolidated joint ventures, net 4,301 4,291
Harborside South Pier [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 58,492 59,733
Other assets 13,189 12,840
Total assets 71,681 72,573
Mortgages, loans payable and other obligations 70,411 70,690
Other liabilities 6,344 4,982
Partners'/members' capital (deficit) (5,074) (3,099)
Total liabilities and partners'/members' capital (deficit) 71,681 72,573
Company's investments in unconsolidated joint ventures, net (1,331) (343)
Red Bank Corporate Plaza [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 22,745 22,903
Other assets 3,108 2,909
Total assets 25,853 25,812
Mortgages, loans payable and other obligations 17,914 18,100
Other liabilities 138 117
Partners'/members' capital (deficit) 7,801 7,595
Total liabilities and partners'/members' capital (deficit) 25,853 25,812
Company's investments in unconsolidated joint ventures, net 3,787 3,676
Gramercy Agreement [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 39,025 39,276
Other assets 5,713 5,669
Total assets 44,738 44,945
Mortgages, loans payable and other obligations 50,978 50,978
Other liabilities 1,255 1,086
Partners'/members' capital (deficit) (7,495) (7,119)
Total liabilities and partners'/members' capital (deficit) 44,738 44,945
12 Vreeland [Member]
    
Schedule of Equity Method Investments [Line Items]    
Rental property, net 14,144 13,122
Other assets 484 521
Total assets 14,628 13,643
Mortgages, loans payable and other obligations 652 1,207
Other liabilities   168
Partners'/members' capital (deficit) 13,976 12,268
Total liabilities and partners'/members' capital (deficit) 14,628 13,643
Company's investments in unconsolidated joint ventures, net 10,432 10,233
Boston-Downtown Crossing [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 45,986 46,121
Total assets 45,986 46,121
Partners'/members' capital (deficit) 45,986 46,121
Total liabilities and partners'/members' capital (deficit) 45,986 46,121
Company's investments in unconsolidated joint ventures, net 13,049 13,005
Gale Jefferson [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 2,987 2,927
Total assets 2,987 2,927
Partners'/members' capital (deficit) 2,987 2,927
Total liabilities and partners'/members' capital (deficit) 2,987 2,927
Company's investments in unconsolidated joint ventures, net 1,173 1,153
Stamford SM LLC [Member]
    
Schedule of Equity Method Investments [Line Items]    
Other assets 40,485  
Total assets 40,485  
Partners'/members' capital (deficit) 40,485  
Total liabilities and partners'/members' capital (deficit) 40,485  
Company's investments in unconsolidated joint ventures, net $ 32,388