Quarterly report pursuant to Section 13 or 15(d)

Commitments And Contingencies (Narrative) (Details)

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Commitments And Contingencies (Narrative) (Details) (USD $)
3 Months Ended 9 Months Ended 3 Months Ended 9 Months Ended 3 Months Ended 9 Months Ended 1 Months Ended 9 Months Ended 12 Months Ended 1 Months Ended 9 Months Ended 1 Months Ended 3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Harborside Plaza 4-A Agreement [Member]
Sep. 30, 2011
Harborside Plaza 4-A Agreement [Member]
Sep. 30, 2012
Harborside Plaza 4-A Agreement [Member]
Sep. 30, 2011
Harborside Plaza 4-A Agreement [Member]
Sep. 30, 2012
Harborside Plaza 5 Agreement [Member]
Sep. 30, 2011
Harborside Plaza 5 Agreement [Member]
Sep. 30, 2012
Harborside Plaza 5 Agreement [Member]
Sep. 30, 2011
Harborside Plaza 5 Agreement [Member]
Sep. 30, 2012
Property Lock-Ups [Member]
property
Sep. 30, 2012
Property Lock-Ups Expired [Member]
property
Dec. 31, 2011
Harborside Residential Project [Member]
item
Sep. 30, 2012
Harborside Residential Project [Member]
Dec. 31, 2011
Harborside Residential Project [Member]
item
Sep. 30, 2012
Ironstate Development LLC [Member]
Aug. 31, 2011
Wyndham [Member]
sqft
item
Sep. 30, 2012
Wyndham [Member]
Sep. 30, 2012
Wyndham [Member]
Land [Member]
Jul. 31, 2012
Wegmans Food Markets, Inc. [Member]
sqft
Sep. 30, 2012
Wegmans Food Markets, Inc. [Member]
Sep. 30, 2012
Wegmans Food Markets, Inc. [Member]
Sep. 30, 2012
Maximum [Member]
Wyndham [Member]
Sep. 30, 2012
Minimum [Member]
Wyndham [Member]
Commitments And Contingencies [Line Items]                                                    
Project period             20 years       20 years                              
Percentage of PILOT on project costs             2.00%       2.00%                              
Total project costs         $ 49,500,000           $ 170,900,000                         $ 12,100,000    
Payments in lieu of property taxes (PILOT)         247,000 247,000 742,000 742,000 854,000 854,000 2,600,000 2,600,000                            
Ground lease expense incurred 102,000 102,000 305,000 305,000                                            
Number of properties                         7 127                        
Properties aggregate net book value                         129,600,000 1,700,000,000                        
Expiration year                         2016                          
Area of building, square feet                                     203,000     140,000        
Lease term                                     15 years 3 months              
Number of lease extension options                                     2              
Lease extension term                                                 10 years 5 years
Delivery date to tenant                                     first quarter of 2013              
Total estimated costs of the project                             243,000,000       53,500,000              
Costs of the project incurred                                       $ 30,700,000 $ 13,000,000   $ 500,000      
Number of apartment units in each tower                             766   766                  
Holding and distribution pattern under operating agreement                               Pursuant to the Development Agreement, the Company and Ironstate shall co-develop the Harborside Residential Project with Ironstate responsible for obtaining all required development permits and approvals. Major decisions with respect to the Harborside Residential Project will require the consent of the Company and Ironstate. The Company and Ironstate will have 85 and 15 percent interests, respectively, in the Harborside Residential Project. The Company will receive capital credit of $30 per approved developable square foot for its land.                    
Percentage of interest in venture                             85.00%   85.00%                  
Ownership percentage of third party venture                                   15.00%                
Capital credit receivable per square foot                                 30