Annual report pursuant to Section 13 and 15(d)

Real Estate Investments And Accumulated Depreciation (Schedule Of Real Estate Investments And Accumulated Depreciation) (Details)

v3.10.0.1
Real Estate Investments And Accumulated Depreciation (Schedule Of Real Estate Investments And Accumulated Depreciation) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Related Encumbrances $ 1,406,239      
Initial Costs, Land 788,528      
Initial Costs, Building and Improvements 3,429,551      
Costs Capitalized Subsequent to Acquisition 811,324      
Gross Amount at Which Carried at Close of Period, Land 807,236      
Gross Amount at Which Carried at Close of Period, Building and Improvements 4,498,781      
Total 5,306,017 $ 5,102,844 $ 4,804,867 $ 4,807,718
Accumulated Depreciation 1,097,868 $ 1,087,083 $ 1,332,073 $ 1,464,482
Real Estate Aggregate Cost, Tax Purpose $ 5,100,000      
Office [Member] | One Bridge Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1981      
Acquired 1996      
Initial Costs, Land $ 2,439      
Initial Costs, Building and Improvements 24,462      
Costs Capitalized Subsequent to Acquisition 7,436      
Gross Amount at Which Carried at Close of Period, Land 2,439      
Gross Amount at Which Carried at Close of Period, Building and Improvements 31,898      
Total 34,337      
Accumulated Depreciation $ 17,658      
Office [Member] | 150 J.F. Kennedy Parkway [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1980      
Acquired 1997      
Initial Costs, Land $ 12,606      
Initial Costs, Building and Improvements 50,425      
Costs Capitalized Subsequent to Acquisition 17,073      
Gross Amount at Which Carried at Close of Period, Land 12,606      
Gross Amount at Which Carried at Close of Period, Building and Improvements 67,498      
Total 80,104      
Accumulated Depreciation $ 33,259      
Office [Member] | 51 J.F. Kennedy Parkway [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 2017      
Related Encumbrances $ 69,459      
Initial Costs, Land 5,873      
Initial Costs, Building and Improvements 100,359      
Costs Capitalized Subsequent to Acquisition 575      
Gross Amount at Which Carried at Close of Period, Land 5,873      
Gross Amount at Which Carried at Close of Period, Building and Improvements 100,934      
Total 106,807      
Accumulated Depreciation $ 6,806      
Office [Member] | 101 J.F. Kennedy Parkway [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1981      
Acquired 2017      
Related Encumbrances $ 29,197      
Initial Costs, Land 4,380      
Initial Costs, Building and Improvements 59,730      
Costs Capitalized Subsequent to Acquisition 1,151      
Gross Amount at Which Carried at Close of Period, Land 4,380      
Gross Amount at Which Carried at Close of Period, Building and Improvements 60,881      
Total 65,261      
Accumulated Depreciation $ 4,063      
Office [Member] | 103 J.F. Kennedy Parkway [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1981      
Acquired 2017      
Related Encumbrances $ 24,875      
Initial Costs, Land 3,158      
Initial Costs, Building and Improvements 50,813      
Costs Capitalized Subsequent to Acquisition 469      
Gross Amount at Which Carried at Close of Period, Land 3,158      
Gross Amount at Which Carried at Close of Period, Building and Improvements 51,282      
Total 54,440      
Accumulated Depreciation $ 3,434      
Office [Member] | 111 River Street [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2002      
Acquired 2016      
Initial Costs, Land $ 204      
Initial Costs, Building and Improvements 198,609      
Costs Capitalized Subsequent to Acquisition 14,932      
Gross Amount at Which Carried at Close of Period, Building and Improvements 213,745      
Total 213,745      
Accumulated Depreciation $ 14,364      
Office [Member] | Harborside Plaza 1 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 1996      
Initial Costs, Land $ 3,923      
Initial Costs, Building and Improvements 51,013      
Costs Capitalized Subsequent to Acquisition 26,426      
Gross Amount at Which Carried at Close of Period, Land 3,923      
Gross Amount at Which Carried at Close of Period, Building and Improvements 77,439      
Total 81,362      
Accumulated Depreciation $ 41,749      
Office [Member] | Harborside Plaza 2 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1996      
Initial Costs, Land $ 17,655      
Initial Costs, Building and Improvements 101,546      
Costs Capitalized Subsequent to Acquisition 53,393      
Gross Amount at Which Carried at Close of Period, Land 8,364      
Gross Amount at Which Carried at Close of Period, Building and Improvements 164,230      
Total 172,594      
Accumulated Depreciation $ 69,838      
Office [Member] | Harborside Plaza 3 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1996      
Initial Costs, Land $ 17,655      
Initial Costs, Building and Improvements 101,878      
Costs Capitalized Subsequent to Acquisition 53,060      
Gross Amount at Which Carried at Close of Period, Land 8,363      
Gross Amount at Which Carried at Close of Period, Building and Improvements 164,230      
Total 172,593      
Accumulated Depreciation $ 69,838      
Office [Member] | Harborside Plaza 4A [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2000      
Acquired 2000      
Initial Costs, Land $ 1,244      
Initial Costs, Building and Improvements 56,144      
Costs Capitalized Subsequent to Acquisition 8,688      
Gross Amount at Which Carried at Close of Period, Land 1,244      
Gross Amount at Which Carried at Close of Period, Building and Improvements 64,832      
Total 66,076      
Accumulated Depreciation $ 31,301      
Office [Member] | Harborside Plaza 5 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2002      
Acquired 2002      
Initial Costs, Land $ 6,218      
Initial Costs, Building and Improvements 170,682      
Costs Capitalized Subsequent to Acquisition 60,698      
Gross Amount at Which Carried at Close of Period, Land 5,705      
Gross Amount at Which Carried at Close of Period, Building and Improvements 231,893      
Total 237,598      
Accumulated Depreciation $ 101,850      
Office [Member] | 101 Hudson [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1992      
Acquired 2005      
Related Encumbrances $ 248,460      
Initial Costs, Land 45,530      
Initial Costs, Building and Improvements 271,376      
Costs Capitalized Subsequent to Acquisition 33,508      
Gross Amount at Which Carried at Close of Period, Land 45,530      
Gross Amount at Which Carried at Close of Period, Building and Improvements 304,884      
Total 350,414      
Accumulated Depreciation $ 103,639      
Office [Member] | 100 Overlook Center [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1997      
Initial Costs, Land $ 2,378      
Initial Costs, Building and Improvements 21,754      
Costs Capitalized Subsequent to Acquisition 4,577      
Gross Amount at Which Carried at Close of Period, Land 2,378      
Gross Amount at Which Carried at Close of Period, Building and Improvements 26,331      
Total 28,709      
Accumulated Depreciation $ 13,218      
Office [Member] | 5 Vaughn Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1995      
Initial Costs, Land $ 657      
Initial Costs, Building and Improvements 9,800      
Costs Capitalized Subsequent to Acquisition 1,564      
Gross Amount at Which Carried at Close of Period, Land 657      
Gross Amount at Which Carried at Close of Period, Building and Improvements 11,364      
Total 12,021      
Accumulated Depreciation $ 6,529      
Office [Member] | 333 Thornall Street [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 2015      
Initial Costs, Land $ 5,542      
Initial Costs, Building and Improvements 40,762      
Costs Capitalized Subsequent to Acquisition 3,686      
Gross Amount at Which Carried at Close of Period, Land 5,542      
Gross Amount at Which Carried at Close of Period, Building and Improvements 44,448      
Total 49,990      
Accumulated Depreciation $ 4,933      
Office [Member] | 343 Thornall Street [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1991      
Acquired 2006      
Initial Costs, Land $ 6,027      
Initial Costs, Building and Improvements 39,101      
Costs Capitalized Subsequent to Acquisition 15,160      
Gross Amount at Which Carried at Close of Period, Land 6,027      
Gross Amount at Which Carried at Close of Period, Building and Improvements 54,261      
Total 60,288      
Accumulated Depreciation $ 16,308      
Office [Member] | 101 Wood Avenue South [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 2016      
Initial Costs, Land $ 8,509      
Initial Costs, Building and Improvements 72,738      
Costs Capitalized Subsequent to Acquisition 1,183      
Gross Amount at Which Carried at Close of Period, Land 7,384      
Gross Amount at Which Carried at Close of Period, Building and Improvements 75,046      
Total 82,430      
Accumulated Depreciation $ 6,936      
Office [Member] | 500 College Road East [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 1998      
Initial Costs, Land $ 614      
Initial Costs, Building and Improvements 20,626      
Costs Capitalized Subsequent to Acquisition 5,776      
Gross Amount at Which Carried at Close of Period, Land 614      
Gross Amount at Which Carried at Close of Period, Building and Improvements 26,402      
Total 27,016      
Accumulated Depreciation $ 14,225      
Office [Member] | 581 Main Street [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1991      
Acquired 1997      
Initial Costs, Land $ 3,237      
Initial Costs, Building and Improvements 12,949      
Costs Capitalized Subsequent to Acquisition 35,315      
Gross Amount at Which Carried at Close of Period, Land 8,115      
Gross Amount at Which Carried at Close of Period, Building and Improvements 43,386      
Total 51,501      
Accumulated Depreciation $ 16,482      
Office [Member] | 23 Main Street [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1977      
Acquired 2005      
Initial Costs, Land $ 4,336      
Initial Costs, Building and Improvements 19,544      
Costs Capitalized Subsequent to Acquisition 6,377      
Gross Amount at Which Carried at Close of Period, Land 4,336      
Gross Amount at Which Carried at Close of Period, Building and Improvements 25,921      
Total 30,257      
Accumulated Depreciation $ 8,116      
Office [Member] | One River Center, Building 1 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 2004      
Initial Costs, Land $ 3,070      
Initial Costs, Building and Improvements 17,414      
Costs Capitalized Subsequent to Acquisition 16,094      
Gross Amount at Which Carried at Close of Period, Land 2,451      
Gross Amount at Which Carried at Close of Period, Building and Improvements 34,127      
Total 36,578      
Accumulated Depreciation $ 8,385      
Office [Member] | One River Center, Building 2 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 2004      
Initial Costs, Land $ 2,468      
Initial Costs, Building and Improvements 15,043      
Costs Capitalized Subsequent to Acquisition 4,175      
Gross Amount at Which Carried at Close of Period, Land 2,452      
Gross Amount at Which Carried at Close of Period, Building and Improvements 19,234      
Total 21,686      
Accumulated Depreciation $ 7,880      
Office [Member] | One River Center, Building 3 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 2004      
Initial Costs, Land $ 4,051      
Initial Costs, Building and Improvements 24,790      
Costs Capitalized Subsequent to Acquisition 5,688      
Gross Amount at Which Carried at Close of Period, Land 4,627      
Gross Amount at Which Carried at Close of Period, Building and Improvements 29,902      
Total 34,529      
Accumulated Depreciation $ 11,525      
Office [Member] | 3600 Route 66 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1995      
Initial Costs, Land $ 1,098      
Initial Costs, Building and Improvements 18,146      
Costs Capitalized Subsequent to Acquisition 11,461      
Gross Amount at Which Carried at Close of Period, Land 1,098      
Gross Amount at Which Carried at Close of Period, Building and Improvements 29,607      
Total 30,705      
Accumulated Depreciation $ 15,555      
Office [Member] | 100 Schultz Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 2017      
Initial Costs, Land $ 1,953      
Initial Costs, Building and Improvements 6,790      
Costs Capitalized Subsequent to Acquisition 1,126      
Gross Amount at Which Carried at Close of Period, Land 1,953      
Gross Amount at Which Carried at Close of Period, Building and Improvements 7,916      
Total 9,869      
Accumulated Depreciation $ 905      
Office [Member] | 200 Schultz Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 2017      
Initial Costs, Land $ 2,184      
Initial Costs, Building and Improvements 8,259      
Costs Capitalized Subsequent to Acquisition 1,165      
Gross Amount at Which Carried at Close of Period, Land 2,184      
Gross Amount at Which Carried at Close of Period, Building and Improvements 9,424      
Total 11,608      
Accumulated Depreciation $ 1,003      
Office [Member] | 325 Columbia Parkway [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1994      
Initial Costs, Land $ 1,564      
Costs Capitalized Subsequent to Acquisition 18,616      
Gross Amount at Which Carried at Close of Period, Land 1,564      
Gross Amount at Which Carried at Close of Period, Building and Improvements 18,616      
Total 20,180      
Accumulated Depreciation $ 13,036      
Office [Member] | 1 Giralda Farms [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1982      
Acquired 2017      
Initial Costs, Land $ 3,370      
Initial Costs, Building and Improvements 27,145      
Costs Capitalized Subsequent to Acquisition 734      
Gross Amount at Which Carried at Close of Period, Land 3,370      
Gross Amount at Which Carried at Close of Period, Building and Improvements 27,879      
Total 31,249      
Accumulated Depreciation $ 2,260      
Office [Member] | 7 Giralda Farms [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1997      
Acquired 2017      
Initial Costs, Land $ 5,402      
Initial Costs, Building and Improvements 5,402      
Costs Capitalized Subsequent to Acquisition 510      
Gross Amount at Which Carried at Close of Period, Land 5,402      
Gross Amount at Which Carried at Close of Period, Building and Improvements 38,174      
Total 43,576      
Accumulated Depreciation $ 2,766      
Office [Member] | 4 Campus Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 2001      
Initial Costs, Land $ 5,213      
Initial Costs, Building and Improvements 20,984      
Costs Capitalized Subsequent to Acquisition 4,052      
Gross Amount at Which Carried at Close of Period, Land 5,213      
Gross Amount at Which Carried at Close of Period, Building and Improvements 25,036      
Total 30,249      
Accumulated Depreciation $ 11,490      
Office [Member] | 6 Campus Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 2001      
Initial Costs, Land $ 4,411      
Initial Costs, Building and Improvements 17,796      
Costs Capitalized Subsequent to Acquisition 3,945      
Gross Amount at Which Carried at Close of Period, Land 4,411      
Gross Amount at Which Carried at Close of Period, Building and Improvements 21,741      
Total 26,152      
Accumulated Depreciation $ 9,665      
Office [Member] | 7 Campus Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1982      
Acquired 1998      
Initial Costs, Land $ 1,932      
Initial Costs, Building and Improvements 27,788      
Costs Capitalized Subsequent to Acquisition 6,757      
Gross Amount at Which Carried at Close of Period, Land 1,932      
Gross Amount at Which Carried at Close of Period, Building and Improvements 34,545      
Total 36,477      
Accumulated Depreciation $ 18,408      
Office [Member] | 8 Campus Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1998      
Initial Costs, Land $ 1,865      
Initial Costs, Building and Improvements 35,456      
Costs Capitalized Subsequent to Acquisition 12,475      
Gross Amount at Which Carried at Close of Period, Land 1,865      
Gross Amount at Which Carried at Close of Period, Building and Improvements 47,931      
Total 49,796      
Accumulated Depreciation $ 22,089      
Office [Member] | 9 Campus Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 2001      
Initial Costs, Land $ 3,277      
Initial Costs, Building and Improvements 11,796      
Costs Capitalized Subsequent to Acquisition 22,721      
Gross Amount at Which Carried at Close of Period, Land 5,842      
Gross Amount at Which Carried at Close of Period, Building and Improvements 31,952      
Total 37,794      
Accumulated Depreciation $ 13,474      
Office [Member] | 2 Dryden Way [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1998      
Initial Costs, Land $ 778      
Initial Costs, Building and Improvements 420      
Costs Capitalized Subsequent to Acquisition 110      
Gross Amount at Which Carried at Close of Period, Land 778      
Gross Amount at Which Carried at Close of Period, Building and Improvements 530      
Total 1,308      
Accumulated Depreciation $ 320      
Office [Member] | 4 Gatehall Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 2000      
Initial Costs, Land $ 8,452      
Initial Costs, Building and Improvements 33,929      
Costs Capitalized Subsequent to Acquisition 7,788      
Gross Amount at Which Carried at Close of Period, Land 8,452      
Gross Amount at Which Carried at Close of Period, Building and Improvements 41,717      
Total 50,169      
Accumulated Depreciation $ 18,726      
Office [Member] | 2 Hilton Court [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1991      
Acquired 1998      
Initial Costs, Land $ 1,971      
Initial Costs, Building and Improvements 32,007      
Costs Capitalized Subsequent to Acquisition 4,474      
Gross Amount at Which Carried at Close of Period, Land 1,971      
Gross Amount at Which Carried at Close of Period, Building and Improvements 36,481      
Total 38,452      
Accumulated Depreciation $ 19,992      
Office [Member] | 1 Sylvan Way [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1998      
Initial Costs, Land $ 1,689      
Initial Costs, Building and Improvements 24,699      
Costs Capitalized Subsequent to Acquisition 4,984      
Gross Amount at Which Carried at Close of Period, Land 1,021      
Gross Amount at Which Carried at Close of Period, Building and Improvements 30,351      
Total 31,372      
Accumulated Depreciation $ 14,094      
Office [Member] | 3 Sylvan Way [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 2015      
Initial Costs, Land $ 5,590      
Initial Costs, Building and Improvements 4,710      
Costs Capitalized Subsequent to Acquisition 9,840      
Gross Amount at Which Carried at Close of Period, Land 5,590      
Gross Amount at Which Carried at Close of Period, Building and Improvements 14,550      
Total 20,140      
Accumulated Depreciation $ 845      
Office [Member] | 5 Sylvan Way [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1998      
Initial Costs, Land $ 1,160      
Initial Costs, Building and Improvements 25,214      
Costs Capitalized Subsequent to Acquisition 7,056      
Gross Amount at Which Carried at Close of Period, Land 1,161      
Gross Amount at Which Carried at Close of Period, Building and Improvements 32,269      
Total 33,430      
Accumulated Depreciation $ 14,774      
Office [Member] | 7 Sylvan Way [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1998      
Initial Costs, Land $ 2,084      
Initial Costs, Building and Improvements 26,083      
Costs Capitalized Subsequent to Acquisition 14,823      
Gross Amount at Which Carried at Close of Period, Land 2,084      
Gross Amount at Which Carried at Close of Period, Building and Improvements 40,906      
Total 42,990      
Accumulated Depreciation $ 15,697      
Office [Member] | 5 Wood Hollow Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1979      
Acquired 2004      
Initial Costs, Land $ 5,302      
Initial Costs, Building and Improvements 26,488      
Costs Capitalized Subsequent to Acquisition 21,087      
Gross Amount at Which Carried at Close of Period, Land 5,302      
Gross Amount at Which Carried at Close of Period, Building and Improvements 47,575      
Total 52,877      
Accumulated Depreciation $ 21,689      
Office [Member] | 100 Clearbrook Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1975      
Acquired 1997      
Initial Costs, Land $ 220      
Initial Costs, Building and Improvements 5,366      
Costs Capitalized Subsequent to Acquisition 1,846      
Gross Amount at Which Carried at Close of Period, Land 220      
Gross Amount at Which Carried at Close of Period, Building and Improvements 7,212      
Total 7,432      
Accumulated Depreciation $ 3,620      
Office [Member] | 101 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1971      
Acquired 1997      
Initial Costs, Land $ 267      
Initial Costs, Building and Improvements 5,838      
Costs Capitalized Subsequent to Acquisition $ (6,105)      
Office [Member] | 1 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1980      
Acquired 1997      
Initial Costs, Land $ 66      
Initial Costs, Building and Improvements 1,711      
Costs Capitalized Subsequent to Acquisition 210      
Gross Amount at Which Carried at Close of Period, Land 66      
Gross Amount at Which Carried at Close of Period, Building and Improvements 1,921      
Total 1,987      
Accumulated Depreciation $ 1,102      
Office [Member] | 2 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1997      
Initial Costs, Land $ 109      
Initial Costs, Building and Improvements 3,128      
Costs Capitalized Subsequent to Acquisition 1,474      
Gross Amount at Which Carried at Close of Period, Land 109      
Gross Amount at Which Carried at Close of Period, Building and Improvements 4,602      
Total 4,711      
Accumulated Depreciation $ 2,909      
Office [Member] | 7 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1998      
Initial Costs, Land $ 330      
Initial Costs, Building and Improvements 13,013      
Costs Capitalized Subsequent to Acquisition 2,733      
Gross Amount at Which Carried at Close of Period, Land 330      
Gross Amount at Which Carried at Close of Period, Building and Improvements 15,746      
Total 16,076      
Accumulated Depreciation $ 8,071      
Office [Member] | 17 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1997      
Initial Costs, Building and Improvements $ 7,269      
Costs Capitalized Subsequent to Acquisition 1,248      
Gross Amount at Which Carried at Close of Period, Building and Improvements 8,517      
Total 8,517      
Accumulated Depreciation $ 4,547      
Office [Member] | 1 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1982      
Acquired 1997      
Initial Costs, Land $ 1,104      
Initial Costs, Building and Improvements 11,904      
Costs Capitalized Subsequent to Acquisition 3,688      
Gross Amount at Which Carried at Close of Period, Land 1,105      
Gross Amount at Which Carried at Close of Period, Building and Improvements 15,591      
Total 16,696      
Accumulated Depreciation $ 8,210      
Office [Member] | 3 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1997      
Initial Costs, Land $ 385      
Initial Costs, Building and Improvements 6,256      
Costs Capitalized Subsequent to Acquisition 1,803      
Gross Amount at Which Carried at Close of Period, Land 385      
Gross Amount at Which Carried at Close of Period, Building and Improvements 8,059      
Total 8,444      
Accumulated Depreciation $ 4,496      
Office [Member] | 3 Odell Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 2003      
Initial Costs, Land $ 1,322      
Initial Costs, Building and Improvements 4,777      
Costs Capitalized Subsequent to Acquisition 2,360      
Gross Amount at Which Carried at Close of Period, Land 1,322      
Gross Amount at Which Carried at Close of Period, Building and Improvements 7,137      
Total 8,459      
Accumulated Depreciation $ 3,976      
Office And Office/Flex Buildings [Member] | 11 Clearbrook Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1974      
Acquired 1997      
Initial Costs, Land $ 149      
Initial Costs, Building and Improvements 2,159      
Costs Capitalized Subsequent to Acquisition 504      
Gross Amount at Which Carried at Close of Period, Land 149      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,663      
Total 2,812      
Accumulated Depreciation $ 1,479      
Office And Office/Flex Buildings [Member] | 75 Clearbrook Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1997      
Initial Costs, Land $ 2,314      
Initial Costs, Building and Improvements 4,716      
Costs Capitalized Subsequent to Acquisition 57      
Gross Amount at Which Carried at Close of Period, Land 2,314      
Gross Amount at Which Carried at Close of Period, Building and Improvements 4,773      
Total 7,087      
Accumulated Depreciation $ 2,621      
Office And Office/Flex Buildings [Member] | 125 Clearbrook Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2002      
Acquired 2002      
Initial Costs, Land $ 1,055      
Initial Costs, Building and Improvements 3,676      
Costs Capitalized Subsequent to Acquisition (292)      
Gross Amount at Which Carried at Close of Period, Land 1,055      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,384      
Total 4,439      
Accumulated Depreciation $ 1,685      
Office And Office/Flex Buildings [Member] | 150 Clearbrook Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1975      
Acquired 1997      
Initial Costs, Land $ 497      
Initial Costs, Building and Improvements 7,030      
Costs Capitalized Subsequent to Acquisition 2,198      
Gross Amount at Which Carried at Close of Period, Land 497      
Gross Amount at Which Carried at Close of Period, Building and Improvements 9,228      
Total 9,725      
Accumulated Depreciation $ 4,927      
Office And Office/Flex Buildings [Member] | 175 Clearbrook Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1973      
Acquired 1997      
Initial Costs, Land $ 655      
Initial Costs, Building and Improvements 7,473      
Costs Capitalized Subsequent to Acquisition 973      
Gross Amount at Which Carried at Close of Period, Land 655      
Gross Amount at Which Carried at Close of Period, Building and Improvements 8,446      
Total 9,101      
Accumulated Depreciation $ 4,731      
Office And Office/Flex Buildings [Member] | 200 Clearbrook Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1974      
Acquired 1997      
Initial Costs, Land $ 579      
Initial Costs, Building and Improvements 6,620      
Costs Capitalized Subsequent to Acquisition 1,667      
Gross Amount at Which Carried at Close of Period, Land 579      
Gross Amount at Which Carried at Close of Period, Building and Improvements 8,287      
Total 8,866      
Accumulated Depreciation $ 4,343      
Office And Office/Flex Buildings [Member] | 250 Clearbrook Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1973      
Acquired 1997      
Initial Costs, Land $ 867      
Initial Costs, Building and Improvements 8,647      
Costs Capitalized Subsequent to Acquisition 2,387      
Gross Amount at Which Carried at Close of Period, Land 867      
Gross Amount at Which Carried at Close of Period, Building and Improvements 11,034      
Total 11,901      
Accumulated Depreciation $ 5,813      
Office And Office/Flex Buildings [Member] | 50 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1969      
Acquired 1997      
Initial Costs, Land $ 237      
Initial Costs, Building and Improvements 2,617      
Costs Capitalized Subsequent to Acquisition 540      
Gross Amount at Which Carried at Close of Period, Land 237      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,157      
Total 3,394      
Accumulated Depreciation $ 1,731      
Office And Office/Flex Buildings [Member] | 77 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1977      
Acquired 1997      
Initial Costs, Land $ 34      
Initial Costs, Building and Improvements 1,104      
Costs Capitalized Subsequent to Acquisition 179      
Gross Amount at Which Carried at Close of Period, Land 34      
Gross Amount at Which Carried at Close of Period, Building and Improvements 1,283      
Total 1,317      
Accumulated Depreciation $ 740      
Office And Office/Flex Buildings [Member] | 85 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1968      
Acquired 1997      
Initial Costs, Land $ 155      
Initial Costs, Building and Improvements 2,507      
Costs Capitalized Subsequent to Acquisition 456      
Gross Amount at Which Carried at Close of Period, Land 155      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,963      
Total 3,118      
Accumulated Depreciation $ 1,584      
Office And Office/Flex Buildings [Member] | 300 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1970      
Acquired 1997      
Initial Costs, Land $ 460      
Initial Costs, Building and Improvements 3,609      
Costs Capitalized Subsequent to Acquisition 307      
Gross Amount at Which Carried at Close of Period, Land 460      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,916      
Total 4,376      
Accumulated Depreciation $ 2,132      
Office And Office/Flex Buildings [Member] | 350 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1970      
Acquired 1997      
Initial Costs, Land $ 100      
Initial Costs, Building and Improvements 1,793      
Costs Capitalized Subsequent to Acquisition 175      
Gross Amount at Which Carried at Close of Period, Land 100      
Gross Amount at Which Carried at Close of Period, Building and Improvements 1,968      
Total 2,068      
Accumulated Depreciation $ 1,146      
Office And Office/Flex Buildings [Member] | 399 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1962      
Acquired 1997      
Initial Costs, Land $ 531      
Initial Costs, Building and Improvements 7,191      
Costs Capitalized Subsequent to Acquisition 163      
Gross Amount at Which Carried at Close of Period, Land 531      
Gross Amount at Which Carried at Close of Period, Building and Improvements 7,354      
Total 7,885      
Accumulated Depreciation $ 4,077      
Office And Office/Flex Buildings [Member] | 400 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1970      
Acquired 1997      
Initial Costs, Land $ 2,202      
Initial Costs, Building and Improvements 1,846      
Costs Capitalized Subsequent to Acquisition 1,140      
Gross Amount at Which Carried at Close of Period, Land 2,202      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,986      
Total 5,188      
Accumulated Depreciation $ 1,807      
Office And Office/Flex Buildings [Member] | 500 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1970      
Acquired 1997      
Initial Costs, Land $ 258      
Initial Costs, Building and Improvements 4,183      
Costs Capitalized Subsequent to Acquisition 508      
Gross Amount at Which Carried at Close of Period, Land 258      
Gross Amount at Which Carried at Close of Period, Building and Improvements 4,691      
Total 4,949      
Accumulated Depreciation $ 2,655      
Office And Office/Flex Buildings [Member] | 525 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1972      
Acquired 1997      
Initial Costs, Land $ 345      
Initial Costs, Building and Improvements 5,499      
Costs Capitalized Subsequent to Acquisition 837      
Gross Amount at Which Carried at Close of Period, Land 345      
Gross Amount at Which Carried at Close of Period, Building and Improvements 6,336      
Total 6,681      
Accumulated Depreciation $ 3,661      
Office And Office/Flex Buildings [Member] | 1 Westchester Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1967      
Acquired 1997      
Initial Costs, Land $ 199      
Initial Costs, Building and Improvements 2,023      
Costs Capitalized Subsequent to Acquisition 183      
Gross Amount at Which Carried at Close of Period, Land 199      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,206      
Total 2,405      
Accumulated Depreciation $ 1,214      
Office And Office/Flex Buildings [Member] | 2 Westchester Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1968      
Acquired 1997      
Initial Costs, Land $ 234      
Initial Costs, Building and Improvements 2,726      
Costs Capitalized Subsequent to Acquisition 914      
Gross Amount at Which Carried at Close of Period, Land 234      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,640      
Total 3,874      
Accumulated Depreciation $ 1,971      
Office And Office/Flex Buildings [Member] | 3 Westchester Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1969      
Acquired 1997      
Initial Costs, Land $ 655      
Initial Costs, Building and Improvements 7,936      
Costs Capitalized Subsequent to Acquisition 1,433      
Gross Amount at Which Carried at Close of Period, Land 655      
Gross Amount at Which Carried at Close of Period, Building and Improvements 9,369      
Total 10,024      
Accumulated Depreciation $ 4,876      
Office And Office/Flex Buildings [Member] | 4 Westchester Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1969      
Acquired 1997      
Initial Costs, Land $ 320      
Initial Costs, Building and Improvements 3,729      
Costs Capitalized Subsequent to Acquisition 1,531      
Gross Amount at Which Carried at Close of Period, Land 320      
Gross Amount at Which Carried at Close of Period, Building and Improvements 5,260      
Total 5,580      
Accumulated Depreciation $ 2,512      
Office And Office/Flex Buildings [Member] | 5 Westchester Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1969      
Acquired 1997      
Initial Costs, Land $ 118      
Initial Costs, Building and Improvements 1,949      
Costs Capitalized Subsequent to Acquisition 303      
Gross Amount at Which Carried at Close of Period, Land 118      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,252      
Total 2,370      
Accumulated Depreciation $ 1,184      
Office And Office/Flex Buildings [Member] | 6 Westchester Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1968      
Acquired 1997      
Initial Costs, Land $ 164      
Initial Costs, Building and Improvements 1,998      
Costs Capitalized Subsequent to Acquisition 202      
Gross Amount at Which Carried at Close of Period, Land 164      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,200      
Total 2,364      
Accumulated Depreciation $ 1,197      
Office And Office/Flex Buildings [Member] | 7 Westchester Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1972      
Acquired 1997      
Initial Costs, Land $ 286      
Initial Costs, Building and Improvements 4,321      
Costs Capitalized Subsequent to Acquisition 1,168      
Gross Amount at Which Carried at Close of Period, Land 286      
Gross Amount at Which Carried at Close of Period, Building and Improvements 5,489      
Total 5,775      
Accumulated Depreciation $ 2,781      
Office And Office/Flex Buildings [Member] | 8 Westchester Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1971      
Acquired 1997      
Initial Costs, Land $ 447      
Initial Costs, Building and Improvements 5,262      
Costs Capitalized Subsequent to Acquisition 2,127      
Gross Amount at Which Carried at Close of Period, Land 447      
Gross Amount at Which Carried at Close of Period, Building and Improvements 7,389      
Total 7,836      
Accumulated Depreciation $ 4,025      
Office And Office/Flex Buildings [Member] | 200 Saw Mill River Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1965      
Acquired 1997      
Initial Costs, Land $ 353      
Initial Costs, Building and Improvements 3,353      
Costs Capitalized Subsequent to Acquisition 833      
Gross Amount at Which Carried at Close of Period, Land 353      
Gross Amount at Which Carried at Close of Period, Building and Improvements 4,186      
Total 4,539      
Accumulated Depreciation $ 2,110      
Office And Office/Flex Buildings [Member] | 4 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1997      
Initial Costs, Land $ 363      
Initial Costs, Building and Improvements 7,513      
Costs Capitalized Subsequent to Acquisition 2,140      
Gross Amount at Which Carried at Close of Period, Land 363      
Gross Amount at Which Carried at Close of Period, Building and Improvements 9,653      
Total 10,016      
Accumulated Depreciation $ 5,635      
Office And Office/Flex Buildings [Member] | 5 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1980      
Acquired 2001      
Initial Costs, Land $ 2,219      
Initial Costs, Building and Improvements 8,916      
Costs Capitalized Subsequent to Acquisition 1,472      
Gross Amount at Which Carried at Close of Period, Land 2,219      
Gross Amount at Which Carried at Close of Period, Building and Improvements 10,388      
Total 12,607      
Accumulated Depreciation $ 5,340      
Office And Office/Flex Buildings [Member] | 6 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1980      
Acquired 2001      
Initial Costs, Land $ 740      
Initial Costs, Building and Improvements 2,971      
Costs Capitalized Subsequent to Acquisition 535      
Gross Amount at Which Carried at Close of Period, Land 740      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,506      
Total 4,246      
Accumulated Depreciation $ 1,942      
Office And Office/Flex Buildings [Member] | 8 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1985      
Acquired 1997      
Initial Costs, Land $ 212      
Initial Costs, Building and Improvements 4,410      
Costs Capitalized Subsequent to Acquisition 836      
Gross Amount at Which Carried at Close of Period, Land 212      
Gross Amount at Which Carried at Close of Period, Building and Improvements 5,246      
Total 5,458      
Accumulated Depreciation $ 3,036      
Office And Office/Flex Buildings [Member] | 10 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1985      
Acquired 1997      
Initial Costs, Land $ 134      
Initial Costs, Building and Improvements 2,799      
Costs Capitalized Subsequent to Acquisition 271      
Gross Amount at Which Carried at Close of Period, Land 134      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,070      
Total 3,204      
Accumulated Depreciation $ 1,630      
Office And Office/Flex Buildings [Member] | 11 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1997      
Initial Costs, Building and Improvements $ 4,788      
Costs Capitalized Subsequent to Acquisition 763      
Gross Amount at Which Carried at Close of Period, Building and Improvements 5,551      
Total 5,551      
Accumulated Depreciation $ 2,906      
Office And Office/Flex Buildings [Member] | 12 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1999      
Acquired 1999      
Initial Costs, Land $ 1,562      
Initial Costs, Building and Improvements 3,254      
Costs Capitalized Subsequent to Acquisition 218      
Gross Amount at Which Carried at Close of Period, Land 1,320      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,714      
Total 5,034      
Accumulated Depreciation $ 1,911      
Office And Office/Flex Buildings [Member] | 15 Skyline Drive [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1997      
Initial Costs, Building and Improvements $ 7,449      
Costs Capitalized Subsequent to Acquisition 1,858      
Gross Amount at Which Carried at Close of Period, Building and Improvements 9,307      
Total 9,307      
Accumulated Depreciation $ 4,537      
Office And Office/Flex Buildings [Member] | 100 Corporate Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1997      
Initial Costs, Land $ 602      
Initial Costs, Building and Improvements 9,910      
Costs Capitalized Subsequent to Acquisition 1,175      
Gross Amount at Which Carried at Close of Period, Land 602      
Gross Amount at Which Carried at Close of Period, Building and Improvements 11,085      
Total 11,687      
Accumulated Depreciation $ 6,143      
Office And Office/Flex Buildings [Member] | 200 Corporate Boulevard South [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1997      
Initial Costs, Land $ 502      
Initial Costs, Building and Improvements 7,575      
Costs Capitalized Subsequent to Acquisition 2,585      
Gross Amount at Which Carried at Close of Period, Land 502      
Gross Amount at Which Carried at Close of Period, Building and Improvements 10,160      
Total 10,662      
Accumulated Depreciation $ 5,017      
Office And Office/Flex Buildings [Member] | 4 Executive Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1986      
Acquired 1997      
Initial Costs, Land $ 584      
Initial Costs, Building and Improvements 6,134      
Costs Capitalized Subsequent to Acquisition 854      
Gross Amount at Which Carried at Close of Period, Land 584      
Gross Amount at Which Carried at Close of Period, Building and Improvements 6,988      
Total 7,572      
Accumulated Depreciation $ 3,723      
Office And Office/Flex Buildings [Member] | 6 Executive Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1997      
Initial Costs, Land $ 546      
Initial Costs, Building and Improvements 7,246      
Costs Capitalized Subsequent to Acquisition 2,212      
Gross Amount at Which Carried at Close of Period, Land 546      
Gross Amount at Which Carried at Close of Period, Building and Improvements 9,458      
Total 10,004      
Accumulated Depreciation $ 5,127      
Office And Office/Flex Buildings [Member] | 1 Odell Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1980      
Acquired 1997      
Initial Costs, Land $ 1,206      
Initial Costs, Building and Improvements 6,815      
Costs Capitalized Subsequent to Acquisition 2,349      
Gross Amount at Which Carried at Close of Period, Land 1,206      
Gross Amount at Which Carried at Close of Period, Building and Improvements 9,164      
Total 10,370      
Accumulated Depreciation $ 5,093      
Office And Office/Flex Buildings [Member] | 5 Odell Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 1997      
Initial Costs, Land $ 331      
Initial Costs, Building and Improvements 2,988      
Costs Capitalized Subsequent to Acquisition 476      
Gross Amount at Which Carried at Close of Period, Land 331      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,464      
Total 3,795      
Accumulated Depreciation $ 2,029      
Office And Office/Flex Buildings [Member] | 7 Odell Plaza [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 1997      
Initial Costs, Land $ 419      
Initial Costs, Building and Improvements 4,418      
Costs Capitalized Subsequent to Acquisition 1,303      
Gross Amount at Which Carried at Close of Period, Land 419      
Gross Amount at Which Carried at Close of Period, Building and Improvements 5,721      
Total 6,140      
Accumulated Depreciation $ 2,938      
Office And Office/Flex Buildings [Member] | 419 West Avenue [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1986      
Acquired 1997      
Initial Costs, Land $ 4,538      
Initial Costs, Building and Improvements 9,246      
Costs Capitalized Subsequent to Acquisition 482      
Gross Amount at Which Carried at Close of Period, Land 4,538      
Gross Amount at Which Carried at Close of Period, Building and Improvements 9,728      
Total 14,266      
Accumulated Depreciation $ 5,316      
Office And Office/Flex Buildings [Member] | 500 West Avenue [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1997      
Initial Costs, Land $ 415      
Initial Costs, Building and Improvements 1,679      
Costs Capitalized Subsequent to Acquisition 646      
Gross Amount at Which Carried at Close of Period, Land 415      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,325      
Total 2,740      
Accumulated Depreciation $ 1,221      
Office And Office/Flex Buildings [Member] | 550 West Avenue [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1997      
Initial Costs, Land $ 1,975      
Initial Costs, Building and Improvements 3,856      
Costs Capitalized Subsequent to Acquisition 133      
Gross Amount at Which Carried at Close of Period, Land 1,975      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,989      
Total 5,964      
Accumulated Depreciation $ 2,172      
Office And Office/Flex Buildings [Member] | 600 West Avenue [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1999      
Acquired 1999      
Initial Costs, Land $ 2,305      
Initial Costs, Building and Improvements 2,863      
Costs Capitalized Subsequent to Acquisition 1,184      
Gross Amount at Which Carried at Close of Period, Land 2,305      
Gross Amount at Which Carried at Close of Period, Building and Improvements 4,047      
Total 6,352      
Accumulated Depreciation $ 1,739      
Office And Office/Flex Buildings [Member] | 650 West Avenue [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1998      
Acquired 1998      
Initial Costs, Land $ 1,328      
Costs Capitalized Subsequent to Acquisition 3,247      
Gross Amount at Which Carried at Close of Period, Land 1,328      
Gross Amount at Which Carried at Close of Period, Building and Improvements 3,247      
Total 4,575      
Accumulated Depreciation $ 1,805      
Retail [Member] | 230 White Plains Road [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 1997      
Initial Costs, Land $ 124      
Initial Costs, Building and Improvements 1,845      
Costs Capitalized Subsequent to Acquisition 288      
Gross Amount at Which Carried at Close of Period, Land 124      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,133      
Total 2,257      
Accumulated Depreciation $ 1,108      
Retail [Member] | 2 Executive Boulevard [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1986      
Acquired 1997      
Initial Costs, Land $ 89      
Initial Costs, Building and Improvements 2,439      
Costs Capitalized Subsequent to Acquisition 107      
Gross Amount at Which Carried at Close of Period, Land 89      
Gross Amount at Which Carried at Close of Period, Building and Improvements 2,546      
Total 2,635      
Accumulated Depreciation $ 1,397      
Multi-Family Properties [Member] | RoseGarden Monaco, L.L.C. [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2011      
Acquired 2017      
Related Encumbrances $ 168,370      
Initial Costs, Land 58,761      
Initial Costs, Building and Improvements 240,871      
Costs Capitalized Subsequent to Acquisition 434      
Gross Amount at Which Carried at Close of Period, Land 58,761      
Gross Amount at Which Carried at Close of Period, Building and Improvements 241,305      
Total 300,066      
Accumulated Depreciation $ 10,720      
Multi-Family Properties [Member] | Marbella I [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2003      
Acquired 2018      
Related Encumbrances $ 130,040      
Initial Costs, Land 48,820      
Initial Costs, Building and Improvements 160,740      
Costs Capitalized Subsequent to Acquisition 1,306      
Gross Amount at Which Carried at Close of Period, Land 48,820      
Gross Amount at Which Carried at Close of Period, Building and Improvements 162,046      
Total 210,866      
Accumulated Depreciation $ 1,711      
Multi-Family Properties [Member] | Port Imperial South 11 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2018      
Acquired 2018      
Related Encumbrances $ 99,792      
Gross Amount at Which Carried at Close of Period, Land 22,047      
Gross Amount at Which Carried at Close of Period, Building and Improvements 108,392      
Total 130,439      
Accumulated Depreciation $ 577      
Multi-Family Properties [Member] | Richmond Court [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1997      
Acquired 2013      
Initial Costs, Land $ 2,992      
Initial Costs, Building and Improvements 13,534      
Costs Capitalized Subsequent to Acquisition 1,908      
Gross Amount at Which Carried at Close of Period, Land 2,992      
Gross Amount at Which Carried at Close of Period, Building and Improvements 15,442      
Total 18,434      
Accumulated Depreciation $ 1,856      
Multi-Family Properties [Member] | Riverwatch Commons [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1995      
Acquired 2013      
Initial Costs, Land $ 4,169      
Initial Costs, Building and Improvements 18,974      
Costs Capitalized Subsequent to Acquisition 2,187      
Gross Amount at Which Carried at Close of Period, Land 4,169      
Gross Amount at Which Carried at Close of Period, Building and Improvements 21,161      
Total 25,330      
Accumulated Depreciation 2,534      
Multi-Family Properties [Member] | Signature Place At Morris Plains [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Related Encumbrances 41,703      
Initial Costs, Land 930      
Costs Capitalized Subsequent to Acquisition 56,373      
Gross Amount at Which Carried at Close of Period, Land 930      
Gross Amount at Which Carried at Close of Period, Building and Improvements 56,373      
Total 57,303      
Accumulated Depreciation $ 922      
Multi-Family Properties [Member] | Quarry Place At Tuckahoe [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Related Encumbrances $ 40,433      
Initial Costs, Land 5,585      
Initial Costs, Building and Improvements 3,400      
Costs Capitalized Subsequent to Acquisition 48,718      
Gross Amount at Which Carried at Close of Period, Land 5,585      
Gross Amount at Which Carried at Close of Period, Building and Improvements 52,118      
Total 57,703      
Accumulated Depreciation $ 2,573      
Multi-Family Properties [Member] | The Chase At Overlook Ridge [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Related Encumbrances $ 134,839      
Initial Costs, Land 11,072      
Initial Costs, Building and Improvements 87,793      
Costs Capitalized Subsequent to Acquisition 74,692      
Gross Amount at Which Carried at Close of Period, Land 21,827      
Gross Amount at Which Carried at Close of Period, Building and Improvements 151,730      
Total 173,557      
Accumulated Depreciation $ 9,969      
Multi-Family Properties [Member] | Portside At Pier One [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Related Encumbrances $ 58,644      
Initial Costs, Building and Improvements 73,713      
Costs Capitalized Subsequent to Acquisition 446      
Gross Amount at Which Carried at Close of Period, Building and Improvements 74,159      
Total 74,159      
Accumulated Depreciation $ 6,163      
Multi-Family Properties [Member] | Portside 5/6 [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2018      
Acquired 2018      
Related Encumbrances $ 96,369      
Gross Amount at Which Carried at Close of Period, Building and Improvements 113,913      
Total 113,913      
Accumulated Depreciation $ 1,268      
Multi-Family Properties [Member] | Alterra At Overlook Ridge IA [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2004      
Acquired 2013      
Related Encumbrances $ 40,102      
Initial Costs, Land 9,042      
Initial Costs, Building and Improvements 50,671      
Costs Capitalized Subsequent to Acquisition 1,072      
Gross Amount at Which Carried at Close of Period, Land 9,042      
Gross Amount at Which Carried at Close of Period, Building and Improvements 51,743      
Total 60,785      
Accumulated Depreciation $ 7,933      
Multi-Family Properties [Member] | Alterra at Overlook Ridge II [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2008      
Acquired 2013      
Related Encumbrances $ 59,371      
Initial Costs, Land 12,055      
Initial Costs, Building and Improvements 71,409      
Costs Capitalized Subsequent to Acquisition 409      
Gross Amount at Which Carried at Close of Period, Land 12,056      
Gross Amount at Which Carried at Close of Period, Building and Improvements 71,817      
Total 83,873      
Accumulated Depreciation $ 10,980      
Other Property [Member] | 100 Avenue At Port Imperial [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Initial Costs, Land $ 350      
Costs Capitalized Subsequent to Acquisition 4,205      
Gross Amount at Which Carried at Close of Period, Land 471      
Gross Amount at Which Carried at Close of Period, Building and Improvements 4,084      
Total 4,555      
Accumulated Depreciation $ 310      
Other Property [Member] | 500 Avenue At Port Imperial [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2013      
Acquired 2013      
Related Encumbrances $ 36,568      
Initial Costs, Land 13,099      
Initial Costs, Building and Improvements 56,669      
Costs Capitalized Subsequent to Acquisition (19,756)      
Gross Amount at Which Carried at Close of Period, Land 13,099      
Gross Amount at Which Carried at Close of Period, Building and Improvements 36,913      
Total 50,012      
Accumulated Depreciation 4,925      
Projects Under Development And Developable Land [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Related Encumbrances 128,017      
Initial Costs, Land 363,373      
Initial Costs, Building and Improvements 494,764      
Gross Amount at Which Carried at Close of Period, Land 363,373      
Gross Amount at Which Carried at Close of Period, Building and Improvements 494,764      
Total 858,137      
Accumulated Depreciation 14,726      
Furniture, Fixtures And Equipment [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Costs Capitalized Subsequent to Acquisition 53,718      
Gross Amount at Which Carried at Close of Period, Building and Improvements 53,718      
Total 53,718      
Accumulated Depreciation $ 15,879      
Buildings And Improvements [Member]        
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]        
Useful Live 40 years