Real Estate Investments And Accumulated Depreciation (Schedule Of Real Estate Investments And Accumulated Depreciation) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Related Encumbrances $ 813,585      
Initial Costs, Land 697,773      
Initial Costs, Building and Improvements 3,457,953      
Costs Capitalized Subsequent to Acquisition 649,141      
Gross Amount at Which Carried at Close of Period, Land [1] 661,335      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,143,532      
Total 4,804,867 [2] $ 4,807,718 $ 4,958,179 $ 5,129,933
Accumulated depreciation 1,332,073 [3] $ 1,464,482 $ 1,414,305 $ 1,400,988
Real Estate Aggregate Cost, Tax Purpose $ 3,100,000      
100 Avenue At Port Imperial [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Initial Costs, Land $ 350      
Costs Capitalized Subsequent to Acquisition 4,185      
Gross Amount at Which Carried at Close of Period, Land [1] 471      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,064      
Total [2] 4,535      
Accumulated depreciation [3] $ 60      
Office [Member] | One Bridge Plaza [Member]        
SEC Schedule III, 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 7,283      
Gross Amount at Which Carried at Close of Period, Land [1] 2,439      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 31,745      
Total [2] 34,184      
Accumulated depreciation [3] $ 15,881      
Office [Member] | 2115 Linwood Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1981      
Acquired 1998      
Initial Costs, Land $ 474      
Initial Costs, Building and Improvements 4,419      
Costs Capitalized Subsequent to Acquisition 7,503      
Gross Amount at Which Carried at Close of Period, Land [1] 474      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 11,922      
Total [2] 12,396      
Accumulated depreciation [3] $ 4,518      
Office [Member] | 135 Chestnut Ridge Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1981      
Acquired 1997      
Initial Costs, Land $ 2,587      
Initial Costs, Building and Improvements 10,350      
Costs Capitalized Subsequent to Acquisition (4,659)      
Gross Amount at Which Carried at Close of Period, Land [1] 1,437      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,841      
Total [2] 8,278      
Accumulated depreciation [3] $ 4,536      
Office [Member] | 15 East Midland Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1997      
Initial Costs, Land $ 10,375      
Initial Costs, Building and Improvements 41,497      
Costs Capitalized Subsequent to Acquisition 2,508      
Gross Amount at Which Carried at Close of Period, Land [1] 10,374      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 44,006      
Total [2] 54,380      
Accumulated depreciation [3] $ 21,052      
Office [Member] | 140 East Ridgewood Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1981      
Acquired 1997      
Initial Costs, Land $ 7,932      
Initial Costs, Building and Improvements 31,463      
Costs Capitalized Subsequent to Acquisition 8,171      
Gross Amount at Which Carried at Close of Period, Land [1] 7,932      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 39,634      
Total [2] 47,566      
Accumulated depreciation [3] $ 19,260      
Office [Member] | 461 From Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1997      
Initial Costs, Land $ 13,194      
Initial Costs, Building and Improvements 52,778      
Costs Capitalized Subsequent to Acquisition 11,533      
Gross Amount at Which Carried at Close of Period, Land [1] 13,194      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 64,311      
Total [2] 77,505      
Accumulated depreciation [3] $ 26,938      
Office [Member] | 650 From Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1978      
Acquired 1997      
Initial Costs, Land $ 10,487      
Initial Costs, Building and Improvements 41,949      
Costs Capitalized Subsequent to Acquisition 8,209      
Gross Amount at Which Carried at Close of Period, Land [1] 10,487      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 50,158      
Total [2] 60,645      
Accumulated depreciation [3] $ 24,199      
Office [Member] | 61 South Paramus Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1985      
Acquired [4] 1997      
Initial Costs, Land [4] $ 9,005      
Initial Costs, Building and Improvements [4] 36,018      
Costs Capitalized Subsequent to Acquisition [4] 10,595      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 9,005      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 46,613      
Total [2],[4] 55,618      
Accumulated depreciation [3],[4] $ 21,611      
Office [Member] | 365 West Passaic Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1976      
Acquired 1997      
Initial Costs, Land $ 4,148      
Initial Costs, Building and Improvements 16,592      
Costs Capitalized Subsequent to Acquisition 5,043      
Gross Amount at Which Carried at Close of Period, Land [1] 4,148      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 21,635      
Total [2] 25,783      
Accumulated depreciation [3] $ 10,029      
Office [Member] | 395 West Passaic Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1979      
Acquired 2006      
Initial Costs, Land $ 2,550      
Initial Costs, Building and Improvements 17,131      
Costs Capitalized Subsequent to Acquisition 1,315      
Gross Amount at Which Carried at Close of Period, Land [1] 2,550      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 18,446      
Total [2] 20,996      
Accumulated depreciation [3] $ 4,967      
Office [Member] | 1 Lake Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1994      
Acquired 1997      
Initial Costs, Land $ 13,952      
Initial Costs, Building and Improvements 55,812      
Costs Capitalized Subsequent to Acquisition (36,310)      
Gross Amount at Which Carried at Close of Period, Land [1] 6,268      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 27,186      
Total [2] 33,454      
Accumulated depreciation [3] $ 21,472      
Office [Member] | 400 Chestnut Ridge Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1982      
Acquired 1997      
Initial Costs, Land $ 4,201      
Initial Costs, Building and Improvements 16,802      
Costs Capitalized Subsequent to Acquisition (9,243)      
Gross Amount at Which Carried at Close of Period, Land [1] 2,312      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,448      
Total [2] 11,760      
Accumulated depreciation [3] $ 4,210      
Office [Member] | 50 Tice Boulevard [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 1994      
Initial Costs, Land $ 4,500      
Costs Capitalized Subsequent to Acquisition 27,735      
Gross Amount at Which Carried at Close of Period, Land [1] 4,500      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 27,735      
Total [2] 32,235      
Accumulated depreciation [3] $ 20,159      
Office [Member] | 300 Tice Boulevard [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1991      
Acquired 1996      
Initial Costs, Land $ 5,424      
Initial Costs, Building and Improvements 29,688      
Costs Capitalized Subsequent to Acquisition 6,641      
Gross Amount at Which Carried at Close of Period, Land [1] 5,424      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 36,329      
Total [2] 41,753      
Accumulated depreciation [3] $ 17,560      
Office [Member] | 150 J.F. Kennedy Parkway [Member]        
SEC Schedule III, 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 13,879      
Gross Amount at Which Carried at Close of Period, Land [1] 12,606      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 64,304      
Total [2] 76,910      
Accumulated depreciation [3] $ 28,231      
Office [Member] | 6 Becker Farm Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 2009      
Initial Costs, Land $ 2,600      
Initial Costs, Building and Improvements 15,548      
Costs Capitalized Subsequent to Acquisition (7,057)      
Gross Amount at Which Carried at Close of Period, Land [1] 1,556      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,535      
Total [2] 11,091      
Accumulated depreciation [3] $ 4,877      
Office [Member] | 75 Livingston Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1985      
Acquired 2009      
Initial Costs, Land $ 1,900      
Initial Costs, Building and Improvements 6,312      
Costs Capitalized Subsequent to Acquisition (1,890)      
Gross Amount at Which Carried at Close of Period, Land [1] 1,281      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 5,041      
Total [2] 6,322      
Accumulated depreciation [3] $ 1,098      
Office [Member] | 85 Livingston Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1985      
Acquired 2009      
Initial Costs, Land $ 2,500      
Initial Costs, Building and Improvements 14,238      
Costs Capitalized Subsequent to Acquisition (8,799)      
Gross Amount at Which Carried at Close of Period, Land [1] 1,234      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,705      
Total [2] 7,939      
Accumulated depreciation [3] $ 3,189      
Office [Member] | 111 River Street [Member]        
SEC Schedule III, 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 10,671      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 209,484      
Total [2] 209,484      
Accumulated depreciation [3] $ 2,766      
Office [Member] | Harborside Plaza 1 [Member]        
SEC Schedule III, 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 28,059      
Gross Amount at Which Carried at Close of Period, Land [1] 3,923      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 79,072      
Total [2] 82,995      
Accumulated depreciation [3] $ 42,198      
Office [Member] | Harborside Plaza 2 [Member]        
SEC Schedule III, 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 27,549      
Gross Amount at Which Carried at Close of Period, Land [1] 8,364      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 138,386      
Total [2] 146,750      
Accumulated depreciation [3] $ 60,054      
Office [Member] | Harborside Plaza 3 [Member]        
SEC Schedule III, 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 27,216      
Gross Amount at Which Carried at Close of Period, Land [1] 8,363      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 138,386      
Total [2] 146,749      
Accumulated depreciation [3] $ 60,054      
Office [Member] | Harborside Plaza 4A [Member]        
SEC Schedule III, 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 8,297      
Gross Amount at Which Carried at Close of Period, Land [1] 1,244      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 64,441      
Total [2] 65,685      
Accumulated depreciation [3] $ 26,763      
Office [Member] | Harborside Plaza 5 [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2002      
Acquired 2002      
Related Encumbrances $ 213,470      
Initial Costs, Land 6,218      
Initial Costs, Building and Improvements 170,682      
Costs Capitalized Subsequent to Acquisition 61,152      
Gross Amount at Which Carried at Close of Period, Land [1] 5,705      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 232,347      
Total [2] 238,052      
Accumulated depreciation [3] $ 91,896      
Office [Member] | 101 Hudson Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1992      
Acquired 2005      
Related Encumbrances $ 248,062      
Initial Costs, Land 45,530      
Initial Costs, Building and Improvements 271,376      
Costs Capitalized Subsequent to Acquisition 17,279      
Gross Amount at Which Carried at Close of Period, Land [1] 45,530      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 288,655      
Total [2] 334,185      
Accumulated depreciation [3] $ 84,447      
Office [Member] | 3 AAA Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1981      
Acquired 2007      
Initial Costs, Land $ 242      
Initial Costs, Building and Improvements 3,218      
Costs Capitalized Subsequent to Acquisition 1,106      
Gross Amount at Which Carried at Close of Period, Land [1] 242      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,324      
Total [2] 4,566      
Accumulated depreciation [3] $ 1,223      
Office [Member] | 700 Horizon Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2007      
Acquired 2007      
Initial Costs, Land $ 490      
Initial Costs, Building and Improvements 43      
Costs Capitalized Subsequent to Acquisition 16,663      
Gross Amount at Which Carried at Close of Period, Land [1] 865      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 16,331      
Total [2] 17,196      
Accumulated depreciation [3] $ 4,537      
Office [Member] | 2 South Gold Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1974      
Acquired 2007      
Initial Costs, Land $ 476      
Initial Costs, Building and Improvements 3,487      
Costs Capitalized Subsequent to Acquisition 853      
Gross Amount at Which Carried at Close of Period, Land [1] 476      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,340      
Total [2] 4,816      
Accumulated depreciation [3] $ 1,121      
Office [Member] | 103 Carnegie Center [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 1996      
Initial Costs, Land $ 2,566      
Initial Costs, Building and Improvements 7,868      
Costs Capitalized Subsequent to Acquisition 3,250      
Gross Amount at Which Carried at Close of Period, Land [1] 2,566      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 11,118      
Total [2] 13,684      
Accumulated depreciation [3] $ 5,798      
Office [Member] | 100 Overlook Center [Member]        
SEC Schedule III, 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 3,665      
Gross Amount at Which Carried at Close of Period, Land [1] 2,378      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 25,419      
Total [2] 27,797      
Accumulated depreciation [3] $ 12,017      
Office [Member] | 5 Vaughn Drive [Member]        
SEC Schedule III, 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 1,906      
Gross Amount at Which Carried at Close of Period, Land [1] 657      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 11,706      
Total [2] 12,363      
Accumulated depreciation [3] $ 6,113      
Office [Member] | 377 Summerhill Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1977      
Acquired 1997      
Initial Costs, Land $ 649      
Initial Costs, Building and Improvements 2,594      
Costs Capitalized Subsequent to Acquisition 324      
Gross Amount at Which Carried at Close of Period, Land [1] 649      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,918      
Total [2] 3,567      
Accumulated depreciation [3] $ 1,431      
Office [Member] | 333 Thornall Street [Member]        
SEC Schedule III, 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 1,411      
Gross Amount at Which Carried at Close of Period, Land [1] 5,542      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 42,173      
Total [2] 47,715      
Accumulated depreciation [3] $ 1,776      
Office [Member] | 343 Thornall Street [Member]        
SEC Schedule III, 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 6,658      
Gross Amount at Which Carried at Close of Period, Land [1] 6,027      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 45,759      
Total [2] 51,786      
Accumulated depreciation [3] $ 13,332      
Office [Member] | 101 Wood Avenue South [Member]        
SEC Schedule III, 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 442      
Gross Amount at Which Carried at Close of Period, Land [1] 7,384      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 74,305      
Total [2] 81,689      
Accumulated depreciation [3] $ 1,605      
Office [Member] | 320 University Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2001      
Acquired 2016      
Initial Costs, Land $ 1,468      
Initial Costs, Building and Improvements 6,253      
Costs Capitalized Subsequent to Acquisition 24      
Gross Amount at Which Carried at Close of Period, Land [1] 1,468      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,277      
Total [2] 7,745      
Accumulated depreciation [3] $ 117      
Office [Member] | 321 University Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2003      
Acquired 2016      
Initial Costs, Land $ 5,837      
Initial Costs, Building and Improvements 9,442      
Costs Capitalized Subsequent to Acquisition 32      
Gross Amount at Which Carried at Close of Period, Land [1] 2,217      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 13,094      
Total [2] 15,311      
Accumulated depreciation [3] $ 448      
Office [Member] | 500 College Road East [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1984      
Acquired [4] 1998      
Initial Costs, Land [4] $ 614      
Initial Costs, Building and Improvements [4] 20,626      
Costs Capitalized Subsequent to Acquisition [4] 4,982      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 614      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 25,608      
Total [2],[4] 26,222      
Accumulated depreciation [3],[4] $ 12,194      
Office [Member] | 581 Main Street [Member]        
SEC Schedule III, 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 26,538      
Gross Amount at Which Carried at Close of Period, Land [1] 8,115      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 34,609      
Total [2] 42,724      
Accumulated depreciation [3] $ 18,120      
Office [Member] | 23 Main Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1977      
Acquired 2005      
Related Encumbrances $ 27,809      
Initial Costs, Land 4,336      
Initial Costs, Building and Improvements 19,544      
Costs Capitalized Subsequent to Acquisition 11,894      
Gross Amount at Which Carried at Close of Period, Land [1] 4,336      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 31,438      
Total [2] 35,774      
Accumulated depreciation [3] $ 14,037      
Office [Member] | One River Center, Building 1 [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 2004      
Related Encumbrances $ 10,538      
Initial Costs, Land 3,070      
Initial Costs, Building and Improvements 17,414      
Costs Capitalized Subsequent to Acquisition 4,279      
Gross Amount at Which Carried at Close of Period, Land [1] 2,451      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 22,312      
Total [2] 24,763      
Accumulated depreciation [3] $ 8,292      
Office [Member] | One River Center, Building 2 [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 2004      
Related Encumbrances $ 11,822      
Initial Costs, Land 2,468      
Initial Costs, Building and Improvements 15,043      
Costs Capitalized Subsequent to Acquisition 3,989      
Gross Amount at Which Carried at Close of Period, Land [1] 2,452      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 19,048      
Total [2] 21,500      
Accumulated depreciation [3] $ 6,252      
Office [Member] | One River Center, Building 3 [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 2004      
Related Encumbrances $ 18,786      
Initial Costs, Land 4,051      
Initial Costs, Building and Improvements 24,790      
Costs Capitalized Subsequent to Acquisition 5,671      
Gross Amount at Which Carried at Close of Period, Land [1] 4,627      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 29,885      
Total [2] 34,512      
Accumulated depreciation [3] $ 9,652      
Office [Member] | 3600 Route 66 [Member]        
SEC Schedule III, 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 11,471      
Gross Amount at Which Carried at Close of Period, Land [1] 1,098      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 29,617      
Total [2] 30,715      
Accumulated depreciation [3] $ 12,818      
Office [Member] | 1305 Campus Parkway [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1995      
Initial Costs, Land $ 335      
Initial Costs, Building and Improvements 2,560      
Costs Capitalized Subsequent to Acquisition 591      
Gross Amount at Which Carried at Close of Period, Land [1] 291      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,195      
Total [2] 3,486      
Accumulated depreciation [3] $ 1,602      
Office [Member] | 1350 Campus Parkway [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1995      
Initial Costs, Land $ 454      
Initial Costs, Building and Improvements 7,134      
Costs Capitalized Subsequent to Acquisition 1,211      
Gross Amount at Which Carried at Close of Period, Land [1] 454      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 8,345      
Total [2] 8,799      
Accumulated depreciation [3] $ 4,251      
Office [Member] | 325 Columbia Parkway [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1994      
Initial Costs, Land $ 1,564      
Costs Capitalized Subsequent to Acquisition 18,070      
Gross Amount at Which Carried at Close of Period, Land [1] 1,564      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 18,070      
Total [2] 19,634      
Accumulated depreciation [3] $ 11,783      
Office [Member] | 201 Littleton Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1979      
Acquired 1997      
Initial Costs, Land $ 2,407      
Initial Costs, Building and Improvements 9,627      
Costs Capitalized Subsequent to Acquisition 3,332      
Gross Amount at Which Carried at Close of Period, Land [1] 2,407      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 12,959      
Total [2] 15,366      
Accumulated depreciation [3] $ 6,134      
Office [Member] | 4 Campus Drive [Member]        
SEC Schedule III, 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 4,072      
Gross Amount at Which Carried at Close of Period, Land [1] 5,213      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 25,056      
Total [2] 30,269      
Accumulated depreciation [3] $ 9,767      
Office [Member] | 6 Campus Drive [Member]        
SEC Schedule III, 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 3,458      
Gross Amount at Which Carried at Close of Period, Land [1] 4,411      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 21,254      
Total [2] 25,665      
Accumulated depreciation [3] $ 8,532      
Office [Member] | 7 Campus Drive [Member]        
SEC Schedule III, 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 7,464      
Gross Amount at Which Carried at Close of Period, Land [1] 1,932      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 35,252      
Total [2] 37,184      
Accumulated depreciation [3] $ 16,937      
Office [Member] | 8 Campus Drive [Member]        
SEC Schedule III, 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 6,182      
Gross Amount at Which Carried at Close of Period, Land [1] 1,865      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 41,638      
Total [2] 43,503      
Accumulated depreciation [3] $ 18,624      
Office [Member] | 9 Campus Drive [Member]        
SEC Schedule III, 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 22,610      
Gross Amount at Which Carried at Close of Period, Land [1] 5,842      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 31,841      
Total [2] 37,683      
Accumulated depreciation [3] $ 11,223      
Office [Member] | 2 Dryden Way [Member]        
SEC Schedule III, 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 [1] 778      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 530      
Total [2] 1,308      
Accumulated depreciation [3] $ 283      
Office [Member] | 4 Gatehall Drive [Member]        
SEC Schedule III, 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 4,315      
Gross Amount at Which Carried at Close of Period, Land [1] 8,452      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 38,244      
Total [2] 46,696      
Accumulated depreciation [3] $ 16,518      
Office [Member] | 2 Hilton Court [Member]        
SEC Schedule III, 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] 1,971      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 36,481      
Total [2] 38,452      
Accumulated depreciation [3] $ 17,756      
Office [Member] | 1633 Littleton Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1978      
Acquired 2002      
Initial Costs, Land $ 2,283      
Initial Costs, Building and Improvements 9,550      
Costs Capitalized Subsequent to Acquisition 507      
Gross Amount at Which Carried at Close of Period, Land [1] 2,355      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,985      
Total [2] 12,340      
Accumulated depreciation [3] $ 9,641      
Office [Member] | 1 Sylvan Way [Member]        
SEC Schedule III, 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 2,593      
Gross Amount at Which Carried at Close of Period, Land [1] 1,021      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 27,960      
Total [2] 28,981      
Accumulated depreciation [3] $ 14,312      
Office [Member] | 3 Sylvan Way [Member]        
SEC Schedule III, 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 238      
Gross Amount at Which Carried at Close of Period, Land [1] 5,590      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,948      
Total [2] 10,538      
Accumulated depreciation [3] $ 118      
Office [Member] | 5 Sylvan Way [Member]        
SEC Schedule III, 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 3,244      
Gross Amount at Which Carried at Close of Period, Land [1] 1,161      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 28,457      
Total [2] 29,618      
Accumulated depreciation [3] $ 13,007      
Office [Member] | 7 Sylvan Way [Member]        
SEC Schedule III, 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 6,800      
Gross Amount at Which Carried at Close of Period, Land [1] 2,084      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 32,883      
Total [2] 34,967      
Accumulated depreciation [3] $ 12,607      
Office [Member] | 20 Waterview Boulevard [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 2009      
Initial Costs, Land $ 4,500      
Initial Costs, Building and Improvements 27,246      
Costs Capitalized Subsequent to Acquisition (4,354)      
Gross Amount at Which Carried at Close of Period, Land [1] 3,816      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 23,576      
Total [2] 27,392      
Accumulated depreciation [3] $ 5,472      
Office [Member] | 35 Waterview Boulevard [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 2006      
Initial Costs, Land $ 5,133      
Initial Costs, Building and Improvements 28,059      
Costs Capitalized Subsequent to Acquisition 1,145      
Gross Amount at Which Carried at Close of Period, Land [1] 5,133      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 29,204      
Total [2] 34,337      
Accumulated depreciation [3] $ 9,026      
Office [Member] | 5 Wood Hollow Road [Member]        
SEC Schedule III, 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 20,070      
Gross Amount at Which Carried at Close of Period, Land [1] 5,302      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 46,558      
Total [2] 51,860      
Accumulated depreciation [3] $ 17,314      
Office [Member] | 999 Riverview Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1995      
Initial Costs, Land $ 476      
Initial Costs, Building and Improvements 6,024      
Costs Capitalized Subsequent to Acquisition 2,139      
Gross Amount at Which Carried at Close of Period, Land [1] 1,102      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,537      
Total [2] 8,639      
Accumulated depreciation [3] $ 3,952      
Office [Member] | 440 Route 22 East [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 2010      
Initial Costs, Land $ 3,986      
Initial Costs, Building and Improvements 13,658      
Costs Capitalized Subsequent to Acquisition $ (17,644)      
Office [Member] | 721 Route 202/206 [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1997      
Initial Costs, Land $ 6,730      
Initial Costs, Building and Improvements 26,919      
Costs Capitalized Subsequent to Acquisition (4,831)      
Gross Amount at Which Carried at Close of Period, Land [1] 5,067      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 23,751      
Total [2] 28,818      
Accumulated depreciation [3] $ 11,944      
Office [Member] | 890 Mountain Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1977      
Acquired 1997      
Initial Costs, Land $ 2,796      
Initial Costs, Building and Improvements 11,185      
Costs Capitalized Subsequent to Acquisition (4,842)      
Gross Amount at Which Carried at Close of Period, Land [1] 1,719      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,420      
Total [2] 9,139      
Accumulated depreciation [3] $ 3,196      
Office [Member] | 100 Clearbrook Road [Member]        
SEC Schedule III, 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 1,793      
Gross Amount at Which Carried at Close of Period, Land [1] 220      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,159      
Total [2] 7,379      
Accumulated depreciation [3] $ 3,551      
Office [Member] | 101 Executive Boulevard [Member]        
SEC Schedule III, 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 (5,542)      
Gross Amount at Which Carried at Close of Period, Land [1] 101      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 462      
Total [2] 563      
Accumulated depreciation [3] $ 3      
Office [Member] | 1 Skyline Drive [Member]        
SEC Schedule III, 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 [1] 66      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,921      
Total [2] 1,987      
Accumulated depreciation [3] $ 996      
Office [Member] | 2 Skyline Drive [Member]        
SEC Schedule III, 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 [1] 109      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,602      
Total [2] 4,711      
Accumulated depreciation [3] $ 2,483      
Office [Member] | 7 Skyline Drive [Member]        
SEC Schedule III, 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 2,850      
Gross Amount at Which Carried at Close of Period, Land [1] 330      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 15,863      
Total [2] 16,193      
Accumulated depreciation [3] $ 7,258      
Office [Member] | 17 Skyline Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1989      
Acquired [4] 1997      
Initial Costs, Building and Improvements [4] $ 7,269      
Costs Capitalized Subsequent to Acquisition [4] 1,484      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 8,753      
Total [2],[4] 8,753      
Accumulated depreciation [3],[4] $ 4,269      
Office [Member] | 1 Barker Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1975      
Acquired 1997      
Initial Costs, Land $ 208      
Initial Costs, Building and Improvements 9,629      
Costs Capitalized Subsequent to Acquisition 3,001      
Gross Amount at Which Carried at Close of Period, Land [1] 207      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 12,631      
Total [2] 12,838      
Accumulated depreciation [3] $ 5,919      
Office [Member] | 3 Barker Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1983      
Acquired 1997      
Initial Costs, Land $ 122      
Initial Costs, Building and Improvements 7,864      
Costs Capitalized Subsequent to Acquisition 1,930      
Gross Amount at Which Carried at Close of Period, Land [1] 122      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,794      
Total [2] 9,916      
Accumulated depreciation [3] $ 4,769      
Office [Member] | 50 Main Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1985      
Acquired 1997      
Initial Costs, Land $ 564      
Initial Costs, Building and Improvements 48,105      
Costs Capitalized Subsequent to Acquisition 15,530      
Gross Amount at Which Carried at Close of Period, Land [1] 564      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 63,635      
Total [2] 64,199      
Accumulated depreciation [3] $ 30,051      
Office [Member] | 11 Martine Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1997      
Initial Costs, Land $ 2,587      
Initial Costs, Building and Improvements 35,123      
Costs Capitalized Subsequent to Acquisition 9,594      
Gross Amount at Which Carried at Close of Period, Land [1] 2,587      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 44,717      
Total [2] 47,304      
Accumulated depreciation [3] $ 17,133      
Office [Member] | 1 Water Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1979      
Acquired 1997      
Initial Costs, Land $ 211      
Initial Costs, Building and Improvements 5,382      
Costs Capitalized Subsequent to Acquisition 1,273      
Gross Amount at Which Carried at Close of Period, Land [1] 211      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,655      
Total [2] 6,866      
Accumulated depreciation [3] $ 4,352      
Office [Member] | 1 Executive Boulevard [Member]        
SEC Schedule III, 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 3,719      
Gross Amount at Which Carried at Close of Period, Land [1] 1,105      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 15,622      
Total [2] 16,727      
Accumulated depreciation [3] $ 7,269      
Office [Member] | 3 Executive Boulevard [Member]        
SEC Schedule III, 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 1,799      
Gross Amount at Which Carried at Close of Period, Land [1] 385      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 8,055      
Total [2] 8,440      
Accumulated depreciation [3] $ 3,913      
Office [Member] | 3 Odell Plaza [Member]        
SEC Schedule III, 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 2,332      
Gross Amount at Which Carried at Close of Period, Land [1] 1,322      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,109      
Total [2] 8,431      
Accumulated depreciation [3] $ 3,498      
Office And Office/Flex Buildings [Member] | 3 Terri Lane [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1991      
Acquired 1998      
Initial Costs, Land $ 652      
Initial Costs, Building and Improvements 3,433      
Costs Capitalized Subsequent to Acquisition 1,517      
Gross Amount at Which Carried at Close of Period, Land [1] 658      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,944      
Total [2] 5,602      
Accumulated depreciation [3] $ 2,281      
Office And Office/Flex Buildings [Member] | 5 Terri Lane [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1992      
Acquired 1998      
Initial Costs, Land $ 564      
Initial Costs, Building and Improvements 3,792      
Costs Capitalized Subsequent to Acquisition 2,417      
Gross Amount at Which Carried at Close of Period, Land [1] 569      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,204      
Total [2] 6,773      
Accumulated depreciation [3] $ 3,104      
Office And Office/Flex Buildings [Member] | 2 Commerce Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1986      
Acquired 1999      
Initial Costs, Land $ 723      
Initial Costs, Building and Improvements 2,893      
Costs Capitalized Subsequent to Acquisition 615      
Gross Amount at Which Carried at Close of Period, Land [1] 723      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,508      
Total [2] 4,231      
Accumulated depreciation [3] $ 1,571      
Office And Office/Flex Buildings [Member] | 101 Commerce Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1998      
Initial Costs, Land $ 422      
Initial Costs, Building and Improvements 3,528      
Costs Capitalized Subsequent to Acquisition 436      
Gross Amount at Which Carried at Close of Period, Land [1] 426      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,960      
Total [2] 4,386      
Accumulated depreciation [3] $ 2,003      
Office And Office/Flex Buildings [Member] | 102 Commerce Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1999      
Initial Costs, Land $ 389      
Initial Costs, Building and Improvements 1,554      
Costs Capitalized Subsequent to Acquisition 543      
Gross Amount at Which Carried at Close of Period, Land [1] 389      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,097      
Total [2] 2,486      
Accumulated depreciation [3] $ 820      
Office And Office/Flex Buildings [Member] | 201 Commerce Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1986      
Acquired 1998      
Initial Costs, Land $ 254      
Initial Costs, Building and Improvements 1,694      
Costs Capitalized Subsequent to Acquisition 421      
Gross Amount at Which Carried at Close of Period, Land [1] 258      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,111      
Total [2] 2,369      
Accumulated depreciation [3] $ 996      
Office And Office/Flex Buildings [Member] | 202 Commerce Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1999      
Initial Costs, Land $ 490      
Initial Costs, Building and Improvements 1,963      
Costs Capitalized Subsequent to Acquisition 462      
Gross Amount at Which Carried at Close of Period, Land [1] 490      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,425      
Total [2] 2,915      
Accumulated depreciation [3] $ 989      
Office And Office/Flex Buildings [Member] | 1 Executive Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1998      
Initial Costs, Land $ 226      
Initial Costs, Building and Improvements 1,453      
Costs Capitalized Subsequent to Acquisition 772      
Gross Amount at Which Carried at Close of Period, Land [1] 228      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,223      
Total [2] 2,451      
Accumulated depreciation [3] $ 1,090      
Office And Office/Flex Buildings [Member] | 2 Executive Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 2000      
Initial Costs, Land $ 801      
Initial Costs, Building and Improvements 3,206      
Costs Capitalized Subsequent to Acquisition 1,157      
Gross Amount at Which Carried at Close of Period, Land [1] 801      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,363      
Total [2] 5,164      
Accumulated depreciation [3] $ 1,742      
Office And Office/Flex Buildings [Member] | 101 Executive Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1998      
Initial Costs, Land $ 241      
Initial Costs, Building and Improvements 2,262      
Costs Capitalized Subsequent to Acquisition 622      
Gross Amount at Which Carried at Close of Period, Land [1] 244      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,881      
Total [2] 3,125      
Accumulated depreciation [3] $ 1,340      
Office And Office/Flex Buildings [Member] | 102 Executive Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1998      
Initial Costs, Land $ 353      
Initial Costs, Building and Improvements 3,607      
Costs Capitalized Subsequent to Acquisition 420      
Gross Amount at Which Carried at Close of Period, Land [1] 357      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,023      
Total [2] 4,380      
Accumulated depreciation [3] $ 1,923      
Office And Office/Flex Buildings [Member] | 225 Executive Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1998      
Initial Costs, Land $ 323      
Initial Costs, Building and Improvements 2,477      
Costs Capitalized Subsequent to Acquisition 557      
Gross Amount at Which Carried at Close of Period, Land [1] 326      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,031      
Total [2] 3,357      
Accumulated depreciation [3] $ 1,378      
Office And Office/Flex Buildings [Member] | 97 Foster Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1982      
Acquired 1998      
Initial Costs, Land $ 208      
Initial Costs, Building and Improvements 1,382      
Costs Capitalized Subsequent to Acquisition 266      
Gross Amount at Which Carried at Close of Period, Land [1] 211      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,645      
Total [2] 1,856      
Accumulated depreciation [3] $ 815      
Office And Office/Flex Buildings [Member] | 1507 Lancer Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1995      
Acquired 1998      
Initial Costs, Land $ 119      
Initial Costs, Building and Improvements 1,106      
Costs Capitalized Subsequent to Acquisition 209      
Gross Amount at Which Carried at Close of Period, Land [1] 120      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,314      
Total [2] 1,434      
Accumulated depreciation [3] $ 664      
Office And Office/Flex Buildings [Member] | 1245 North Church Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1998      
Acquired 2001      
Initial Costs, Land $ 691      
Initial Costs, Building and Improvements 2,810      
Costs Capitalized Subsequent to Acquisition 110      
Gross Amount at Which Carried at Close of Period, Land [1] 691      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,920      
Total [2] 3,611      
Accumulated depreciation [3] $ 1,160      
Office And Office/Flex Buildings [Member] | 1247 North Church Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1998      
Acquired 2001      
Initial Costs, Land $ 805      
Initial Costs, Building and Improvements 3,269      
Costs Capitalized Subsequent to Acquisition 361      
Gross Amount at Which Carried at Close of Period, Land [1] 805      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,630      
Total [2] 4,435      
Accumulated depreciation [3] $ 1,439      
Office And Office/Flex Buildings [Member] | 1256 North Church Street [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1984      
Acquired 1998      
Initial Costs, Land $ 354      
Initial Costs, Building and Improvements 3,098      
Costs Capitalized Subsequent to Acquisition 658      
Gross Amount at Which Carried at Close of Period, Land [1] 357      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,753      
Total [2] 4,110      
Accumulated depreciation [3] $ 1,815      
Office And Office/Flex Buildings [Member] | 840 North Lenola Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1995      
Acquired 1998      
Initial Costs, Land $ 329      
Initial Costs, Building and Improvements 2,366      
Costs Capitalized Subsequent to Acquisition 422      
Gross Amount at Which Carried at Close of Period, Land [1] 333      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,784      
Total [2] 3,117      
Accumulated depreciation [3] $ 1,228      
Office And Office/Flex Buildings [Member] | 844 North Lenola Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1995      
Acquired 1998      
Initial Costs, Land $ 239      
Initial Costs, Building and Improvements 1,714      
Costs Capitalized Subsequent to Acquisition 231      
Gross Amount at Which Carried at Close of Period, Land [1] 241      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,943      
Total [2] 2,184      
Accumulated depreciation [3] $ 959      
Office And Office/Flex Buildings [Member] | 915 North Lenola Road [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1998      
Acquired 2000      
Initial Costs, Land $ 508      
Initial Costs, Building and Improvements 2,034      
Costs Capitalized Subsequent to Acquisition 29      
Gross Amount at Which Carried at Close of Period, Land [1] 508      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,063      
Total [2] 2,571      
Accumulated depreciation [3] $ 851      
Office And Office/Flex Buildings [Member] | 2 Twosome Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2000      
Acquired 2001      
Initial Costs, Land $ 701      
Initial Costs, Building and Improvements 2,807      
Costs Capitalized Subsequent to Acquisition 276      
Gross Amount at Which Carried at Close of Period, Land [1] 701      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,083      
Total [2] 3,784      
Accumulated depreciation [3] $ 1,229      
Office And Office/Flex Buildings [Member] | 30 Twosome Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1997      
Acquired 1998      
Initial Costs, Land $ 234      
Initial Costs, Building and Improvements 1,954      
Costs Capitalized Subsequent to Acquisition 510      
Gross Amount at Which Carried at Close of Period, Land [1] 236      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,462      
Total [2] 2,698      
Accumulated depreciation [3] $ 1,349      
Office And Office/Flex Buildings [Member] | 31 Twosome Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1998      
Acquired 2001      
Initial Costs, Land $ 815      
Initial Costs, Building and Improvements 3,276      
Costs Capitalized Subsequent to Acquisition 258      
Gross Amount at Which Carried at Close of Period, Land [1] 815      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,534      
Total [2] 4,349      
Accumulated depreciation [3] $ 1,433      
Office And Office/Flex Buildings [Member] | 40 Twosome Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1996      
Acquired 1998      
Initial Costs, Land $ 297      
Initial Costs, Building and Improvements 2,393      
Costs Capitalized Subsequent to Acquisition 160      
Gross Amount at Which Carried at Close of Period, Land [1] 301      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,549      
Total [2] 2,850      
Accumulated depreciation [3] $ 1,260      
Office And Office/Flex Buildings [Member] | 41 Twosome Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1998      
Acquired 2001      
Initial Costs, Land $ 605      
Initial Costs, Building and Improvements 2,459      
Costs Capitalized Subsequent to Acquisition 214      
Gross Amount at Which Carried at Close of Period, Land [1] 605      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,673      
Total [2] 3,278      
Accumulated depreciation [3] $ 1,114      
Office And Office/Flex Buildings [Member] | 50 Twosome Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1997      
Acquired 1998      
Initial Costs, Land $ 301      
Initial Costs, Building and Improvements 2,330      
Costs Capitalized Subsequent to Acquisition 441      
Gross Amount at Which Carried at Close of Period, Land [1] 304      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,768      
Total [2] 3,072      
Accumulated depreciation [3] $ 1,180      
Office And Office/Flex Buildings [Member] | 100 Horizon Center Boulevard [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1995      
Initial Costs, Land $ 205      
Initial Costs, Building and Improvements 1,676      
Costs Capitalized Subsequent to Acquisition 732      
Gross Amount at Which Carried at Close of Period, Land [1] 327      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,286      
Total [2] 2,613      
Accumulated depreciation [3] $ 1,124      
Office And Office/Flex Buildings [Member] | 200 Horizon Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1991      
Acquired 1995      
Initial Costs, Land $ 205      
Initial Costs, Building and Improvements 3,027      
Costs Capitalized Subsequent to Acquisition 704      
Gross Amount at Which Carried at Close of Period, Land [1] 359      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,577      
Total [2] 3,936      
Accumulated depreciation [3] $ 1,921      
Office And Office/Flex Buildings [Member] | 300 Horizon Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1995      
Initial Costs, Land $ 379      
Initial Costs, Building and Improvements 4,355      
Costs Capitalized Subsequent to Acquisition 1,991      
Gross Amount at Which Carried at Close of Period, Land [1] 533      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,192      
Total [2] 6,725      
Accumulated depreciation [3] $ 2,891      
Office And Office/Flex Buildings [Member] | 500 Horizon Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1995      
Initial Costs, Land $ 379      
Initial Costs, Building and Improvements 3,395      
Costs Capitalized Subsequent to Acquisition 1,062      
Gross Amount at Which Carried at Close of Period, Land [1] 498      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,338      
Total [2] 4,836      
Accumulated depreciation [3] $ 2,303      
Office And Office/Flex Buildings [Member] | 600 Horizon Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2002      
Acquired 2002      
Initial Costs, Building and Improvements $ 7,549      
Costs Capitalized Subsequent to Acquisition 1,014      
Gross Amount at Which Carried at Close of Period, Land [1] 685      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,878      
Total [2] 8,563      
Accumulated depreciation [3] $ 2,845      
Office And Office/Flex Buildings [Member] | 1325 Campus Parkway [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1995      
Initial Costs, Land $ 270      
Initial Costs, Building and Improvements 2,928      
Costs Capitalized Subsequent to Acquisition 774      
Gross Amount at Which Carried at Close of Period, Land [1] 270      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,702      
Total [2] 3,972      
Accumulated depreciation [3] $ 2,078      
Office And Office/Flex Buildings [Member] | 1340 Campus Parkway [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1992      
Acquired 1995      
Initial Costs, Land $ 489      
Initial Costs, Building and Improvements 4,621      
Costs Capitalized Subsequent to Acquisition 2,528      
Gross Amount at Which Carried at Close of Period, Land [1] 489      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,149      
Total [2] 7,638      
Accumulated depreciation [3] $ 3,688      
Office And Office/Flex Buildings [Member] | 1345 Campus Parkway [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1995      
Acquired 1997      
Initial Costs, Land $ 1,023      
Initial Costs, Building and Improvements 5,703      
Costs Capitalized Subsequent to Acquisition 1,208      
Gross Amount at Which Carried at Close of Period, Land [1] 1,024      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,910      
Total [2] 7,934      
Accumulated depreciation [3] $ 3,440      
Office And Office/Flex Buildings [Member] | 1433 Highway 34 [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1985      
Acquired 1995      
Initial Costs, Land $ 889      
Initial Costs, Building and Improvements 4,321      
Costs Capitalized Subsequent to Acquisition 1,813      
Gross Amount at Which Carried at Close of Period, Land [1] 889      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,134      
Total [2] 7,023      
Accumulated depreciation [3] $ 3,250      
Office And Office/Flex Buildings [Member] | 1320 Wyckoff Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1986      
Acquired 1995      
Initial Costs, Land $ 255      
Initial Costs, Building and Improvements 1,285      
Costs Capitalized Subsequent to Acquisition 315      
Gross Amount at Which Carried at Close of Period, Land [1] 216      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,639      
Total [2] 1,855      
Accumulated depreciation [3] $ 955      
Office And Office/Flex Buildings [Member] | 1324 Wyckoff Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1995      
Initial Costs, Land $ 230      
Initial Costs, Building and Improvements 1,439      
Costs Capitalized Subsequent to Acquisition 345      
Gross Amount at Which Carried at Close of Period, Land [1] 190      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,824      
Total [2] 2,014      
Accumulated depreciation [3] $ 931      
Office And Office/Flex Buildings [Member] | 1 Center Court [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1999      
Acquired 1999      
Initial Costs, Land $ 270      
Initial Costs, Building and Improvements 1,824      
Costs Capitalized Subsequent to Acquisition 594      
Gross Amount at Which Carried at Close of Period, Land [1] 270      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,418      
Total [2] 2,688      
Accumulated depreciation [3] $ 1,082      
Office And Office/Flex Buildings [Member] | 2 Center Court [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1998      
Acquired 1998      
Initial Costs, Land $ 191      
Costs Capitalized Subsequent to Acquisition 2,670      
Gross Amount at Which Carried at Close of Period, Land [1] 191      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,670      
Total [2] 2,861      
Accumulated depreciation [3] $ 1,363      
Office And Office/Flex Buildings [Member] | 11 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1989      
Acquired 1995      
Initial Costs, Land $ 586      
Initial Costs, Building and Improvements 2,986      
Costs Capitalized Subsequent to Acquisition 1,000      
Gross Amount at Which Carried at Close of Period, Land [1] 586      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,986      
Total [2] 4,572      
Accumulated depreciation [3] $ 2,250      
Office And Office/Flex Buildings [Member] | 20 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1992      
Acquired 1995      
Initial Costs, Land $ 516      
Initial Costs, Building and Improvements 3,108      
Costs Capitalized Subsequent to Acquisition 155      
Gross Amount at Which Carried at Close of Period, Land [1] 516      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,263      
Total [2] 3,779      
Accumulated depreciation [3] $ 1,686      
Office And Office/Flex Buildings [Member] | 29 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1990      
Acquired 1995      
Initial Costs, Land $ 586      
Initial Costs, Building and Improvements 3,092      
Costs Capitalized Subsequent to Acquisition 961      
Gross Amount at Which Carried at Close of Period, Land [1] 586      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,053      
Total [2] 4,639      
Accumulated depreciation [3] $ 1,978      
Office And Office/Flex Buildings [Member] | 40 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1987      
Acquired 1995      
Initial Costs, Land $ 516      
Initial Costs, Building and Improvements 3,260      
Costs Capitalized Subsequent to Acquisition 1,427      
Gross Amount at Which Carried at Close of Period, Land [1] 516      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,687      
Total [2] 5,203      
Accumulated depreciation [3] $ 2,420      
Office And Office/Flex Buildings [Member] | 45 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1992      
Acquired 1995      
Initial Costs, Land $ 536      
Initial Costs, Building and Improvements 3,379      
Costs Capitalized Subsequent to Acquisition 584      
Gross Amount at Which Carried at Close of Period, Land [1] 536      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,963      
Total [2] 4,499      
Accumulated depreciation [3] $ 1,981      
Office And Office/Flex Buildings [Member] | 60 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1988      
Acquired 1995      
Initial Costs, Land $ 526      
Initial Costs, Building and Improvements 3,257      
Costs Capitalized Subsequent to Acquisition 381      
Gross Amount at Which Carried at Close of Period, Land [1] 526      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,638      
Total [2] 4,164      
Accumulated depreciation [3] $ 1,785      
Office And Office/Flex Buildings [Member] | 80 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1996      
Acquired 1996      
Initial Costs, Land $ 227      
Costs Capitalized Subsequent to Acquisition 1,370      
Gross Amount at Which Carried at Close of Period, Land [1] 227      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,370      
Total [2] 1,597      
Accumulated depreciation [3] $ 700      
Office And Office/Flex Buildings [Member] | 100 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1996      
Acquired 1996      
Initial Costs, Land $ 226      
Costs Capitalized Subsequent to Acquisition 1,369      
Gross Amount at Which Carried at Close of Period, Land [1] 226      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,369      
Total [2] 1,595      
Accumulated depreciation [3] $ 700      
Office And Office/Flex Buildings [Member] | 120 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1994      
Acquired 1995      
Initial Costs, Land $ 228      
Costs Capitalized Subsequent to Acquisition 1,286      
Gross Amount at Which Carried at Close of Period, Land [1] 229      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,285      
Total [2] 1,514      
Accumulated depreciation [3] $ 703      
Office And Office/Flex Buildings [Member] | 140 Commerce Way [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1994      
Acquired 1995      
Initial Costs, Land $ 229      
Costs Capitalized Subsequent to Acquisition 1,284      
Gross Amount at Which Carried at Close of Period, Land [1] 228      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,285      
Total [2] 1,513      
Accumulated depreciation [3] $ 703      
Office And Office/Flex Buildings [Member] | 11 Clearbrook Road [Member]        
SEC Schedule III, 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 578      
Gross Amount at Which Carried at Close of Period, Land [1] 149      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,737      
Total [2] 2,886      
Accumulated depreciation [3] $ 1,344      
Office And Office/Flex Buildings [Member] | 75 Clearbrook Road [Member]        
SEC Schedule III, 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 [1] 2,314      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,773      
Total [2] 7,087      
Accumulated depreciation [3] $ 2,380      
Office And Office/Flex Buildings [Member] | 125 Clearbrook Road [Member]        
SEC Schedule III, 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 (339)      
Gross Amount at Which Carried at Close of Period, Land [1] 1,055      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,337      
Total [2] 4,392      
Accumulated depreciation [3] $ 1,301      
Office And Office/Flex Buildings [Member] | 150 Clearbrook Road [Member]        
SEC Schedule III, 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 2,129      
Gross Amount at Which Carried at Close of Period, Land [1] 497      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,159      
Total [2] 9,656      
Accumulated depreciation [3] $ 4,296      
Office And Office/Flex Buildings [Member] | 175 Clearbrook Road [Member]        
SEC Schedule III, 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 961      
Gross Amount at Which Carried at Close of Period, Land [1] 655      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 8,434      
Total [2] 9,089      
Accumulated depreciation [3] $ 4,155      
Office And Office/Flex Buildings [Member] | 200 Clearbrook Road [Member]        
SEC Schedule III, 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 1,729      
Gross Amount at Which Carried at Close of Period, Land [1] 579      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 8,349      
Total [2] 8,928      
Accumulated depreciation [3] $ 3,862      
Office And Office/Flex Buildings [Member] | 250 Clearbrook Road [Member]        
SEC Schedule III, 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 2,466      
Gross Amount at Which Carried at Close of Period, Land [1] 867      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 11,113      
Total [2] 11,980      
Accumulated depreciation [3] $ 5,130      
Office And Office/Flex Buildings [Member] | 50 Executive Boulevard [Member]        
SEC Schedule III, 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 [1] 237      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,157      
Total [2] 3,394      
Accumulated depreciation [3] $ 1,510      
Office And Office/Flex Buildings [Member] | 77 Executive Boulevard [Member]        
SEC Schedule III, 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 177      
Gross Amount at Which Carried at Close of Period, Land [1] 34      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,281      
Total [2] 1,315      
Accumulated depreciation [3] $ 651      
Office And Office/Flex Buildings [Member] | 85 Executive Boulevard [Member]        
SEC Schedule III, 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 538      
Gross Amount at Which Carried at Close of Period, Land [1] 155      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,045      
Total [2] 3,200      
Accumulated depreciation [3] $ 1,406      
Office And Office/Flex Buildings [Member] | 300 Executive Boulevard [Member]        
SEC Schedule III, 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 306      
Gross Amount at Which Carried at Close of Period, Land [1] 460      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,915      
Total [2] 4,375      
Accumulated depreciation [3] $ 1,922      
Office And Office/Flex Buildings [Member] | 350 Executive Boulevard [Member]        
SEC Schedule III, 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 [1] 100      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 1,968      
Total [2] 2,068      
Accumulated depreciation [3] $ 1,013      
Office And Office/Flex Buildings [Member] | 399 Executive Boulevard [Member]        
SEC Schedule III, 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 [1] 531      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,354      
Total [2] 7,885      
Accumulated depreciation [3] $ 3,693      
Office And Office/Flex Buildings [Member] | 400 Executive Boulevard [Member]        
SEC Schedule III, 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 1,073      
Gross Amount at Which Carried at Close of Period, Land [1] 2,202      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,919      
Total [2] 5,121      
Accumulated depreciation [3] $ 1,555      
Office And Office/Flex Buildings [Member] | 500 Executive Boulevard [Member]        
SEC Schedule III, 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 434      
Gross Amount at Which Carried at Close of Period, Land [1] 258      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,617      
Total [2] 4,875      
Accumulated depreciation [3] $ 2,418      
Office And Office/Flex Buildings [Member] | 525 Executive Boulevard [Member]        
SEC Schedule III, 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 844      
Gross Amount at Which Carried at Close of Period, Land [1] 345      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 6,343      
Total [2] 6,688      
Accumulated depreciation [3] $ 3,272      
Office And Office/Flex Buildings [Member] | 1 Westchester Plaza [Member]        
SEC Schedule III, 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 472      
Gross Amount at Which Carried at Close of Period, Land [1] 199      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,495      
Total [2] 2,694      
Accumulated depreciation [3] $ 1,416      
Office And Office/Flex Buildings [Member] | 2 Westchester Plaza [Member]        
SEC Schedule III, 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 905      
Gross Amount at Which Carried at Close of Period, Land [1] 234      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,631      
Total [2] 3,865      
Accumulated depreciation [3] $ 1,653      
Office And Office/Flex Buildings [Member] | 3 Westchester Plaza [Member]        
SEC Schedule III, 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 1,764      
Gross Amount at Which Carried at Close of Period, Land [1] 655      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,700      
Total [2] 10,355      
Accumulated depreciation [3] $ 4,719      
Office And Office/Flex Buildings [Member] | 4 Westchester Plaza [Member]        
SEC Schedule III, 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 1,191      
Gross Amount at Which Carried at Close of Period, Land [1] 320      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,920      
Total [2] 5,240      
Accumulated depreciation [3] $ 2,606      
Office And Office/Flex Buildings [Member] | 5 Westchester Plaza [Member]        
SEC Schedule III, 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 304      
Gross Amount at Which Carried at Close of Period, Land [1] 118      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,253      
Total [2] 2,371      
Accumulated depreciation [3] $ 1,161      
Office And Office/Flex Buildings [Member] | 6 Westchester Plaza [Member]        
SEC Schedule III, 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 148      
Gross Amount at Which Carried at Close of Period, Land [1] 164      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,146      
Total [2] 2,310      
Accumulated depreciation [3] $ 1,052      
Office And Office/Flex Buildings [Member] | 7 Westchester Plaza [Member]        
SEC Schedule III, 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 1,116      
Gross Amount at Which Carried at Close of Period, Land [1] 286      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 5,437      
Total [2] 5,723      
Accumulated depreciation [3] $ 2,369      
Office And Office/Flex Buildings [Member] | 8 Westchester Plaza [Member]        
SEC Schedule III, 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 2,122      
Gross Amount at Which Carried at Close of Period, Land [1] 447      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,384      
Total [2] 7,831      
Accumulated depreciation [3] $ 3,420      
Office And Office/Flex Buildings [Member] | 200 Saw Mill River Road [Member]        
SEC Schedule III, 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 533      
Gross Amount at Which Carried at Close of Period, Land [1] 353      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,886      
Total [2] 4,239      
Accumulated depreciation [3] $ 1,945      
Office And Office/Flex Buildings [Member] | 4 Skyline Drive [Member]        
SEC Schedule III, 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 2,980      
Gross Amount at Which Carried at Close of Period, Land [1] 363      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 10,493      
Total [2] 10,856      
Accumulated depreciation [3] $ 5,767      
Office And Office/Flex Buildings [Member] | 5 Skyline Drive [Member]        
SEC Schedule III, 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 1,754      
Gross Amount at Which Carried at Close of Period, Land [1] 2,219      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 10,670      
Total [2] 12,889      
Accumulated depreciation [3] $ 5,095      
Office And Office/Flex Buildings [Member] | 6 Skyline Drive [Member]        
SEC Schedule III, 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 1,502      
Gross Amount at Which Carried at Close of Period, Land [1] 740      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 4,473      
Total [2] 5,213      
Accumulated depreciation [3] $ 2,600      
Office And Office/Flex Buildings [Member] | 8 Skyline Drive [Member]        
SEC Schedule III, 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 777      
Gross Amount at Which Carried at Close of Period, Land [1] 212      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 5,187      
Total [2] 5,399      
Accumulated depreciation [3] $ 2,720      
Office And Office/Flex Buildings [Member] | 10 Skyline Drive [Member]        
SEC Schedule III, 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 750      
Gross Amount at Which Carried at Close of Period, Land [1] 134      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,549      
Total [2] 3,683      
Accumulated depreciation [3] $ 2,042      
Office And Office/Flex Buildings [Member] | 11 Skyline Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1989      
Acquired [4] 1997      
Initial Costs, Building and Improvements [4] $ 4,788      
Costs Capitalized Subsequent to Acquisition [4] 763      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 5,551      
Total [2],[4] 5,551      
Accumulated depreciation [3],[4] $ 2,575      
Office And Office/Flex Buildings [Member] | 12 Skyline Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1999      
Acquired [4] 1999      
Initial Costs, Land [4] $ 1,562      
Initial Costs, Building and Improvements [4] 3,254      
Costs Capitalized Subsequent to Acquisition [4] 218      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 1,320      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 3,714      
Total [2],[4] 5,034      
Accumulated depreciation [3],[4] $ 1,644      
Office And Office/Flex Buildings [Member] | 15 Skyline Drive [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1989      
Acquired [4] 1997      
Initial Costs, Building and Improvements [4] $ 7,449      
Costs Capitalized Subsequent to Acquisition [4] 1,749      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 9,198      
Total [2],[4] 9,198      
Accumulated depreciation [3],[4] $ 3,906      
Office And Office/Flex Buildings [Member] | 100 Corporate Boulevard [Member]        
SEC Schedule III, 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 1,397      
Gross Amount at Which Carried at Close of Period, Land [1] 602      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 11,307      
Total [2] 11,909      
Accumulated depreciation [3] $ 5,696      
Office And Office/Flex Buildings [Member] | 200 Corporate Boulevard South [Member]        
SEC Schedule III, 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 2,296      
Gross Amount at Which Carried at Close of Period, Land [1] 502      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,871      
Total [2] 10,373      
Accumulated depreciation [3] $ 4,799      
Office And Office/Flex Buildings [Member] | 4 Executive Plaza [Member]        
SEC Schedule III, 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 1,142      
Gross Amount at Which Carried at Close of Period, Land [1] 584      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 7,276      
Total [2] 7,860      
Accumulated depreciation [3] $ 3,565      
Office And Office/Flex Buildings [Member] | 6 Executive Plaza [Member]        
SEC Schedule III, 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 2,331      
Gross Amount at Which Carried at Close of Period, Land [1] 546      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,577      
Total [2] 10,123      
Accumulated depreciation [3] $ 4,561      
Office And Office/Flex Buildings [Member] | 1 Odell Plaza [Member]        
SEC Schedule III, 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 2,284      
Gross Amount at Which Carried at Close of Period, Land [1] 1,206      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 9,099      
Total [2] 10,305      
Accumulated depreciation [3] $ 4,403      
Office And Office/Flex Buildings [Member] | 5 Odell Plaza [Member]        
SEC Schedule III, 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 535      
Gross Amount at Which Carried at Close of Period, Land [1] 331      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,523      
Total [2] 3,854      
Accumulated depreciation [3] $ 1,878      
Office And Office/Flex Buildings [Member] | 7 Odell Plaza [Member]        
SEC Schedule III, 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 1,319      
Gross Amount at Which Carried at Close of Period, Land [1] 419      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 5,737      
Total [2] 6,156      
Accumulated depreciation [3] $ 2,664      
Office And Office/Flex Buildings [Member] | 419 West Avenue [Member]        
SEC Schedule III, 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 1,452      
Gross Amount at Which Carried at Close of Period, Land [1] 4,538      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 10,698      
Total [2] 15,236      
Accumulated depreciation [3] $ 5,773      
Office And Office/Flex Buildings [Member] | 500 West Avenue [Member]        
SEC Schedule III, 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 [1] 415      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,325      
Total [2] 2,740      
Accumulated depreciation [3] $ 975      
Office And Office/Flex Buildings [Member] | 550 West Avenue [Member]        
SEC Schedule III, 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] 1,975      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,989      
Total [2] 5,964      
Accumulated depreciation [3] $ 1,960      
Office And Office/Flex Buildings [Member] | 600 West Avenue [Member]        
SEC Schedule III, 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 754      
Gross Amount at Which Carried at Close of Period, Land [1] 2,305      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,617      
Total [2] 5,922      
Accumulated depreciation [3] $ 1,519      
Office And Office/Flex Buildings [Member] | 650 West Avenue [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 1998      
Acquired 1998      
Initial Costs, Land $ 1,328      
Costs Capitalized Subsequent to Acquisition 3,547      
Gross Amount at Which Carried at Close of Period, Land [1] 1,328      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 3,547      
Total [2] 4,875      
Accumulated depreciation [3] $ 1,764      
Industrial/Warehouse Facilities [Member] | 1 Warehouse Lane [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1957      
Acquired [4] 1997      
Initial Costs, Land [4] $ 3      
Initial Costs, Building and Improvements [4] 268      
Costs Capitalized Subsequent to Acquisition [4] 233      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 3      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 501      
Total [2],[4] 504      
Accumulated depreciation [3],[4] $ 253      
Industrial/Warehouse Facilities [Member] | 2 Warehouse Lane [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1957      
Acquired [4] 1997      
Initial Costs, Land [4] $ 4      
Initial Costs, Building and Improvements [4] 672      
Costs Capitalized Subsequent to Acquisition [4] 245      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 4      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 917      
Total [2],[4] 921      
Accumulated depreciation [3],[4] $ 410      
Industrial/Warehouse Facilities [Member] | 3 Warehouse Lane [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1957      
Acquired [4] 1997      
Initial Costs, Land [4] $ 21      
Initial Costs, Building and Improvements [4] 1,948      
Costs Capitalized Subsequent to Acquisition [4] 363      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 21      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 2,311      
Total [2],[4] 2,332      
Accumulated depreciation [3],[4] $ 1,247      
Industrial/Warehouse Facilities [Member] | 4 Warehouse Lane [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1957      
Acquired [4] 1997      
Initial Costs, Land [4] $ 84      
Initial Costs, Building and Improvements [4] 13,393      
Costs Capitalized Subsequent to Acquisition [4] 3,665      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 85      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 17,057      
Total [2],[4] 17,142      
Accumulated depreciation [3],[4] $ 7,832      
Industrial/Warehouse Facilities [Member] | 5 Warehouse Lane [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1957      
Acquired [4] 1997      
Initial Costs, Land [4] $ 19      
Initial Costs, Building and Improvements [4] 4,804      
Costs Capitalized Subsequent to Acquisition [4] 943      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 19      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 5,747      
Total [2],[4] 5,766      
Accumulated depreciation [3],[4] $ 2,930      
Industrial/Warehouse Facilities [Member] | 6 Warehouse Lane [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built [4] 1982      
Acquired [4] 1997      
Initial Costs, Land [4] $ 10      
Initial Costs, Building and Improvements [4] 4,419      
Costs Capitalized Subsequent to Acquisition [4] 2,381      
Gross Amount at Which Carried at Close of Period, Land [1],[4] 10      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1],[4] 6,800      
Total [2],[4] 6,810      
Accumulated depreciation [3],[4] $ 3,006      
Retail [Member] | 230 White Plains Road [Member]        
SEC Schedule III, 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 [1] 124      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,133      
Total [2] 2,257      
Accumulated depreciation [3] $ 982      
Retail [Member] | 2 Executive Boulevard [Member]        
SEC Schedule III, 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 [1] 89      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 2,546      
Total [2] 2,635      
Accumulated depreciation [3] $ 1,253      
Multi-Family Properties [Member] | Richmond Court [Member]        
SEC Schedule III, 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 2,103      
Gross Amount at Which Carried at Close of Period, Land [1] 2,992      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 15,637      
Total [2] 18,629      
Accumulated depreciation [3] $ 1,038      
Multi-Family Properties [Member] | Riverwatch Commons [Member]        
SEC Schedule III, 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 2,354      
Gross Amount at Which Carried at Close of Period, Land [1] 4,169      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 21,328      
Total [2] 25,497      
Accumulated depreciation [3] $ 1,440      
Multi-Family Properties [Member] | Park Square [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2011      
Acquired 2013      
Related Encumbrances $ 27,426      
Initial Costs, Land 4,000      
Initial Costs, Building and Improvements 40,670      
Costs Capitalized Subsequent to Acquisition 309      
Gross Amount at Which Carried at Close of Period, Land [1] 4,000      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 40,979      
Total [2] 44,979      
Accumulated depreciation [3] $ 3,165      
Multi-Family Properties [Member] | Quarry Place At Tuckahoe [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Related Encumbrances $ 26,642      
Initial Costs, Land 5,585      
Initial Costs, Building and Improvements 3,400      
Costs Capitalized Subsequent to Acquisition 47,710      
Gross Amount at Which Carried at Close of Period, Land [1] 5,585      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 51,110      
Total [2] 56,695      
Accumulated depreciation [3] $ 30      
Multi-Family Properties [Member] | The Chase At Overlook Ridge [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Related Encumbrances $ 71,992      
Initial Costs, Land 11,072      
Initial Costs, Building and Improvements 87,793      
Costs Capitalized Subsequent to Acquisition 9      
Gross Amount at Which Carried at Close of Period, Land [1] 11,072      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 87,802      
Total [2] 98,874      
Accumulated depreciation [3] $ 2,188      
Multi-Family Properties [Member] | Chase II At Overlook Ridge [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Related Encumbrances $ 34,366      
Initial Costs, Land 10,755      
Initial Costs, Building and Improvements 10,846      
Costs Capitalized Subsequent to Acquisition 43,181      
Gross Amount at Which Carried at Close of Period, Land [1] 10,755      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 54,027      
Total [2] 64,782      
Accumulated depreciation [3] $ 39      
Multi-Family Properties [Member] | Portside At Pier One [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2016      
Acquired 2016      
Related Encumbrances $ 58,505      
Initial Costs, Building and Improvements 73,713      
Costs Capitalized Subsequent to Acquisition 9      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 73,722      
Total [2] 73,722      
Accumulated depreciation [3] $ 1,675      
Multi-Family Properties [Member] | Alterra At Overlook Ridge IA [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2004      
Acquired 2013      
Initial Costs, Land $ 9,042      
Initial Costs, Building and Improvements 50,671      
Costs Capitalized Subsequent to Acquisition 1,322      
Gross Amount at Which Carried at Close of Period, Land [1] 9,042      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 51,993      
Total [2] 61,035      
Accumulated depreciation [3] $ 5,188      
Multi-Family Properties [Member] | Alterra at Overlook Ridge II [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2008      
Acquired 2013      
Initial Costs, Land $ 12,055      
Initial Costs, Building and Improvements 71,409      
Costs Capitalized Subsequent to Acquisition 485      
Gross Amount at Which Carried at Close of Period, Land [1] 12,055      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 71,894      
Total [2] 83,949      
Accumulated depreciation [3] $ 7,144      
Other Property [Member] | 500 Avenue At Port Imperial [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Year Built 2013      
Acquired 2013      
Related Encumbrances $ 36,228      
Initial Costs, Land 13,099      
Initial Costs, Building and Improvements 56,669      
Costs Capitalized Subsequent to Acquisition (20,587)      
Gross Amount at Which Carried at Close of Period, Land [1] 13,099      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 36,082      
Total [2] 49,181      
Accumulated depreciation [3] 3,066      
Projects Under Development And Developable Land [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Related Encumbrances 27,939      
Initial Costs, Land 229,250      
Initial Costs, Building and Improvements 308,623      
Gross Amount at Which Carried at Close of Period, Land [1] 229,250      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 308,623      
Total [2] 537,873      
Accumulated depreciation [3] 4,966      
Furniture, Fixtures And Equipment [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Costs Capitalized Subsequent to Acquisition 21,230      
Gross Amount at Which Carried at Close of Period, Building and Improvements [1] 21,230      
Total [2] 21,230      
Accumulated depreciation [3] $ 7,186      
Buildings And Improvements [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Useful Live 40 years      
Land Lease [Member] | 700 Executive Boulevard [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Acquired 1997      
Initial Costs, Land $ 970      
Gross Amount at Which Carried at Close of Period, Land [1] 970      
Total [2] $ 970      
Land Lease [Member] | 1 Enterprise Boulevard [Member]        
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]        
Acquired 1997      
Initial Costs, Land $ 1,379      
Costs Capitalized Subsequent to Acquisition 1      
Gross Amount at Which Carried at Close of Period, Land [1] 1,380      
Total [2] $ 1,380      
[1] The aggregate cost for federal income tax purposes at December 31, 2016 was approximately $3.1 billion.
[2] Properties identified as held for sale at December 31, 2016 are excluded.
[3] Depreciation of buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.
[4] This property is located on land leased by the Company.