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Real Estate and Accumulated Depreciation Schedule of Real Estate and Accumulated Depreciation (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Encumbrances [1] $ 2,063,087  
Original Land 4,759,821  
Original Building 11,416,957  
Costs Capitalized Subsequent to Acquisition 3,937,798  
Land and improvements 4,879,020  
Buildings and Improvements 13,950,941  
Land Held for Development [2] 246,656  
Development and Construction in Progress 1,037,959  
Total 20,114,576  
Accumulated Depreciation 4,201,891  
Furniture, fixtures and equipment 32,687 $ 29,852
Furniture, fixtures and equipment accumulated depreciation 20,344  
Real Estate Aggregate Cost For Tax Purposes 15,800,000  
Real Estate Aggregate Accumulated Depreciation For Tax Purposes $ 3,200,000  
Real Estate and Accumulated Depreciation, Life Used for Depreciation 40 years  
Unamortized balance of historical fair value adjustments $ 33,830  
Unamortized deferred finance costs $ (2,358)  
767 Fifth Avenue (the General Motors Building)    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 767 Fifth Avenue (the General Motors Building)  
Type Office  
Location New York, NY  
Encumbrances $ 1,333,625  
Original Land 1,796,252  
Original Building 1,532,654  
Costs Capitalized Subsequent to Acquisition 75,211  
Land and improvements 1,796,252  
Buildings and Improvements 1,607,865  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 3,404,117  
Accumulated Depreciation $ 189,209  
Year(s) built / renovated 1968  
Year(s) Acquired 2013  
Depreciable Lives (Years) [3] -1  
Prudential Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Prudential Center  
Type Office  
Location Boston, MA  
Encumbrances $ 0  
Original Land 92,077  
Original Building 734,594  
Costs Capitalized Subsequent to Acquisition 656,606  
Land and improvements 115,638  
Buildings and Improvements 1,214,787  
Land Held for Development 0  
Development and Construction in Progress 152,852  
Total 1,483,277  
Accumulated Depreciation $ 482,661  
Year(s) built / renovated 1965/1993/2002/2016  
Year(s) Acquired 1998/1999/2000  
Depreciable Lives (Years) [3] -1  
Embarcadero Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Embarcadero Center  
Type Office  
Location San Francisco, CA  
Encumbrances $ 0  
Original Land 179,697  
Original Building 847,410  
Costs Capitalized Subsequent to Acquisition 343,726  
Land and improvements 195,987  
Buildings and Improvements 1,174,846  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 1,370,833  
Accumulated Depreciation $ 560,416  
Year(s) built / renovated 1970/1989  
Year(s) Acquired 1998-1999  
Depreciable Lives (Years) [3] -1  
399 Park Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 399 Park Avenue  
Type Office  
Location New York, NY  
Encumbrances $ 0  
Original Land 339,200  
Original Building 700,358  
Costs Capitalized Subsequent to Acquisition 132,062  
Land and improvements 354,107  
Buildings and Improvements 817,513  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 1,171,620  
Accumulated Depreciation $ 287,748  
Year(s) built / renovated 1961  
Year(s) Acquired 2002  
Depreciable Lives (Years) [3] -1  
200 Clarendon Street and Garage    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 200 Clarendon Street and Garage  
Type Office  
Location Boston, MA  
Encumbrances $ 0  
Original Land 219,543  
Original Building 667,884  
Costs Capitalized Subsequent to Acquisition 115,996  
Land and improvements 219,616  
Buildings and Improvements 777,557  
Land Held for Development 6,250  
Development and Construction in Progress 0  
Total 1,003,423  
Accumulated Depreciation $ 140,629  
Year(s) built / renovated 1976  
Year(s) Acquired 2010  
Depreciable Lives (Years) [3] -1  
601 Lexington Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 601 Lexington Avenue  
Type Office  
Location New York, NY  
Encumbrances $ 684,858  
Original Land 241,600  
Original Building 494,782  
Costs Capitalized Subsequent to Acquisition 196,359  
Land and improvements 289,639  
Buildings and Improvements 620,487  
Land Held for Development 0  
Development and Construction in Progress 22,615  
Total 932,741  
Accumulated Depreciation $ 239,984  
Year(s) built / renovated 1977/1997  
Year(s) Acquired 2001  
Depreciable Lives (Years) [3] -1  
250 West 55th Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 250 West 55th Street  
Type Office  
Location New York, NY  
Encumbrances $ 0  
Original Land 285,263  
Original Building 603,167  
Costs Capitalized Subsequent to Acquisition 35,668  
Land and improvements 285,263  
Buildings and Improvements 638,835  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 924,098  
Accumulated Depreciation $ 49,852  
Year(s) built / renovated 2014  
Year(s) Acquired 2007  
Depreciable Lives (Years) [3] -1  
Times Square Tower    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Times Square Tower  
Type Office  
Location New York, NY  
Encumbrances $ 0  
Original Land 165,413  
Original Building 380,438  
Costs Capitalized Subsequent to Acquisition 87,583  
Land and improvements 169,193  
Buildings and Improvements 464,241  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 633,434  
Accumulated Depreciation $ 178,904  
Year(s) built / renovated 2004  
Year(s) Acquired 2000  
Depreciable Lives (Years) [3] -1  
Carnegie Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Carnegie Center  
Type Office  
Location Princeton, NJ  
Encumbrances $ 0  
Original Land 105,107  
Original Building 377,259  
Costs Capitalized Subsequent to Acquisition 149,576  
Land and improvements 106,734  
Buildings and Improvements 522,654  
Land Held for Development 2,554  
Development and Construction in Progress 0  
Total 631,942  
Accumulated Depreciation $ 211,035  
Year(s) built / renovated 1983-2016  
Year(s) Acquired 1998/1999/2000/2007/2014  
Depreciable Lives (Years) [3] -1  
100 Federal Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 100 Federal Street  
Type Office  
Location Boston, MA  
Encumbrances $ 0  
Original Land 131,067  
Original Building 435,954  
Costs Capitalized Subsequent to Acquisition 38,611  
Land and improvements 131,067  
Buildings and Improvements 474,565  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 605,632  
Accumulated Depreciation $ 77,409  
Year(s) built / renovated 1971-1975  
Year(s) Acquired 2012  
Depreciable Lives (Years) [3] -1  
Atlantic Wharf    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Atlantic Wharf  
Type Office  
Location Boston, MA  
Encumbrances $ 0  
Original Land 63,988  
Original Building 454,537  
Costs Capitalized Subsequent to Acquisition 17,442  
Land and improvements 63,988  
Buildings and Improvements 471,979  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 535,967  
Accumulated Depreciation $ 85,984  
Year(s) built / renovated 2011  
Year(s) Acquired 2007  
Depreciable Lives (Years) [3] -1  
Fountain Square    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Fountain Square  
Type Office  
Location Reston, VA  
Encumbrances $ 0  
Original Land 56,853  
Original Building 306,298  
Costs Capitalized Subsequent to Acquisition 17,748  
Land and improvements 56,853  
Buildings and Improvements 320,759  
Land Held for Development 3,287  
Development and Construction in Progress 0  
Total 380,899  
Accumulated Depreciation $ 50,106  
Year(s) built / renovated 1986-1990  
Year(s) Acquired 2012  
Depreciable Lives (Years) [3] -1  
510 Madison Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 510 Madison Avenue  
Type Office  
Location New York, NY  
Encumbrances $ 0  
Original Land 103,000  
Original Building 253,665  
Costs Capitalized Subsequent to Acquisition 21,952  
Land and improvements 103,000  
Buildings and Improvements 275,617  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 378,617  
Accumulated Depreciation $ 44,515  
Year(s) built / renovated 2012  
Year(s) Acquired 2010  
Depreciable Lives (Years) [3] -1  
599 Lexington Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 599 Lexington Avenue  
Type Office  
Location New York, NY  
Encumbrances $ 0  
Original Land 81,040  
Original Building 100,507  
Costs Capitalized Subsequent to Acquisition 169,222  
Land and improvements 87,852  
Buildings and Improvements 262,917  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 350,769  
Accumulated Depreciation $ 168,776  
Year(s) built / renovated 1986  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
680 Folsom Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 680 Folsom Street  
Type Office  
Location San Francisco, CA  
Encumbrances $ 0  
Original Land 72,545  
Original Building 219,766  
Costs Capitalized Subsequent to Acquisition 7,352  
Land and improvements 72,545  
Buildings and Improvements 227,118  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 299,663  
Accumulated Depreciation $ 21,845  
Year(s) built / renovated 2014  
Year(s) Acquired 2012  
Depreciable Lives (Years) [3] -1  
South of Market and Democracy Tower    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name South of Market and Democracy Tower  
Type Office  
Location Reston, VA  
Encumbrances $ 0  
Original Land 13,603  
Original Building 237,479  
Costs Capitalized Subsequent to Acquisition 15,455  
Land and improvements 13,687  
Buildings and Improvements 252,850  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 266,537  
Accumulated Depreciation $ 79,868  
Year(s) built / renovated 2008-2009  
Year(s) Acquired 2003  
Depreciable Lives (Years) [3] -1  
601 Massachusetts Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 601 Massachusetts Avenue  
Type Office  
Location Washington, DC  
Encumbrances $ 0  
Original Land 95,310  
Original Building 165,173  
Costs Capitalized Subsequent to Acquisition 12  
Land and improvements 95,322  
Buildings and Improvements 165,173  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 260,495  
Accumulated Depreciation $ 6,534  
Year(s) built / renovated 2016  
Year(s) Acquired 2008  
Depreciable Lives (Years) [3] -1  
Bay Colony Corporate Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Bay Colony Corporate Center  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 18,789  
Original Building 148,451  
Costs Capitalized Subsequent to Acquisition 68,371  
Land and improvements 18,789  
Buildings and Improvements 216,822  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 235,611  
Accumulated Depreciation $ 46,015  
Year(s) built / renovated 1985-1989  
Year(s) Acquired 2011  
Depreciable Lives (Years) [3] -1  
Gateway Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Gateway Center  
Type Office  
Location San Francisco, CA  
Encumbrances $ 0  
Original Land 28,255  
Original Building 139,245  
Costs Capitalized Subsequent to Acquisition 55,680  
Land and improvements 30,627  
Buildings and Improvements 192,553  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 223,180  
Accumulated Depreciation $ 98,003  
Year(s) built / renovated 1984/1986/2002  
Year(s) Acquired 1999  
Depreciable Lives (Years) [3] -1  
535 Mission Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 535 Mission Street  
Type Office  
Location San Francisco, CA  
Encumbrances $ 0  
Original Land 40,933  
Original Building 148,378  
Costs Capitalized Subsequent to Acquisition 2,015  
Land and improvements 40,933  
Buildings and Improvements 150,393  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 191,326  
Accumulated Depreciation $ 8,844  
Year(s) built / renovated 2015  
Year(s) Acquired 2013  
Depreciable Lives (Years) [3] -1  
2200 Pennsylvania Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 2200 Pennsylvania Avenue  
Type Office  
Location Washington, DC  
Encumbrances $ 0  
Original Land 0  
Original Building 183,541  
Costs Capitalized Subsequent to Acquisition 5,047  
Land and improvements 0  
Buildings and Improvements 188,588  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 188,588  
Accumulated Depreciation $ 39,956  
Year(s) built / renovated 2011  
Year(s) Acquired 2008  
Depreciable Lives (Years) [3] -1  
Mountain View Research Park    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Mountain View Research Park  
Type Office  
Location Mountain View, CA  
Encumbrances $ 0  
Original Land 95,066  
Original Building 68,373  
Costs Capitalized Subsequent to Acquisition 6,491  
Land and improvements 95,066  
Buildings and Improvements 74,864  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 169,930  
Accumulated Depreciation $ 12,849  
Year(s) built / renovated 1977-1981/2007-2013  
Year(s) Acquired 2013  
Depreciable Lives (Years) [3] -1  
Reservoir Place    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Reservoir Place  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 18,605  
Original Building 92,619  
Costs Capitalized Subsequent to Acquisition 53,163  
Land and improvements 20,118  
Buildings and Improvements 129,712  
Land Held for Development 0  
Development and Construction in Progress 14,557  
Total 164,387  
Accumulated Depreciation $ 61,362  
Year(s) built / renovated 1955/1987  
Year(s) Acquired 1997/1998  
Depreciable Lives (Years) [3] -1  
1330 Connecticut Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 1330 Connecticut Avenue  
Type Office  
Location Washington, DC  
Encumbrances $ 0  
Original Land 25,982  
Original Building 82,311  
Costs Capitalized Subsequent to Acquisition 32,276  
Land and improvements 27,135  
Buildings and Improvements 113,434  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 140,569  
Accumulated Depreciation $ 34,137  
Year(s) built / renovated 1984  
Year(s) Acquired 2004  
Depreciable Lives (Years) [3] -1  
1333 New Hampshire Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 1333 New Hampshire Avenue  
Type Office  
Location Washington, DC  
Encumbrances $ 0  
Original Land 34,032  
Original Building 85,660  
Costs Capitalized Subsequent to Acquisition 11,147  
Land and improvements 35,382  
Buildings and Improvements 95,457  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 130,839  
Accumulated Depreciation $ 37,996  
Year(s) built / renovated 1996  
Year(s) Acquired 2003  
Depreciable Lives (Years) [3] -1  
Kingstowne Towne Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Kingstowne Towne Center  
Type Office  
Location Alexandria, VA  
Encumbrances $ 0  
Original Land 18,021  
Original Building 109,038  
Costs Capitalized Subsequent to Acquisition 1,083  
Land and improvements 18,062  
Buildings and Improvements 110,080  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 128,142  
Accumulated Depreciation $ 36,551  
Year(s) built / renovated 2003-2006  
Year(s) Acquired 2007  
Depreciable Lives (Years) [3] -1  
Capital Gallery    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Capital Gallery  
Type Office  
Location Washington, DC  
Encumbrances $ 0  
Original Land 4,725  
Original Building 29,565  
Costs Capitalized Subsequent to Acquisition 89,028  
Land and improvements 8,662  
Buildings and Improvements 114,656  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 123,318  
Accumulated Depreciation $ 61,569  
Year(s) built / renovated 1981/2006  
Year(s) Acquired 2007  
Depreciable Lives (Years) [3] -1  
One Freedom Square    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name One Freedom Square  
Type Office  
Location Reston, VA  
Encumbrances $ 0  
Original Land 9,929  
Original Building 84,504  
Costs Capitalized Subsequent to Acquisition 28,646  
Land and improvements 11,293  
Buildings and Improvements 111,786  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 123,079  
Accumulated Depreciation $ 45,550  
Year(s) built / renovated 2000  
Year(s) Acquired 2003  
Depreciable Lives (Years) [3] -1  
Weston Corporate Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Weston Corporate Center  
Type Office  
Location Weston, MA  
Encumbrances $ 0  
Original Land 25,753  
Original Building 92,312  
Costs Capitalized Subsequent to Acquisition (123)  
Land and improvements 25,854  
Buildings and Improvements 92,088  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 117,942  
Accumulated Depreciation $ 20,074  
Year(s) built / renovated 2010  
Year(s) Acquired 2001  
Depreciable Lives (Years) [3] -1  
Two Freedom Square    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Two Freedom Square  
Type Office  
Location Reston, VA  
Encumbrances $ 0  
Original Land 13,930  
Original Building 77,739  
Costs Capitalized Subsequent to Acquisition 22,756  
Land and improvements 15,420  
Buildings and Improvements 99,005  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 114,425  
Accumulated Depreciation $ 44,569  
Year(s) built / renovated 2001  
Year(s) Acquired 2003  
Depreciable Lives (Years) [3] -1  
One and Two Reston Overlook    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name One and Two Reston Overlook  
Type Office  
Location Reston, VA  
Encumbrances $ 0  
Original Land 16,456  
Original Building 66,192  
Costs Capitalized Subsequent to Acquisition 24,634  
Land and improvements 16,179  
Buildings and Improvements 91,103  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 107,282  
Accumulated Depreciation $ 40,513  
Year(s) built / renovated 1999  
Year(s) Acquired 2000  
Depreciable Lives (Years) [3] -1  
Discovery Square    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Discovery Square  
Type Office  
Location Reston, VA  
Encumbrances $ 0  
Original Land 11,198  
Original Building 71,782  
Costs Capitalized Subsequent to Acquisition 22,642  
Land and improvements 12,533  
Buildings and Improvements 93,089  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 105,622  
Accumulated Depreciation $ 39,605  
Year(s) built / renovated 2001  
Year(s) Acquired 2003  
Depreciable Lives (Years) [3] -1  
140 Kendrick Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 140 Kendrick Street  
Type Office  
Location Needham, MA  
Encumbrances $ 0  
Original Land 18,095  
Original Building 66,905  
Costs Capitalized Subsequent to Acquisition 15,466  
Land and improvements 19,092  
Buildings and Improvements 81,374  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 100,466  
Accumulated Depreciation $ 26,141  
Year(s) built / renovated 2000  
Year(s) Acquired 2004  
Depreciable Lives (Years) [3] -1  
355 Main Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 355 Main Street  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 18,863  
Original Building 53,346  
Costs Capitalized Subsequent to Acquisition 27,658  
Land and improvements 21,173  
Buildings and Improvements 78,694  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 99,867  
Accumulated Depreciation $ 25,345  
Year(s) built / renovated 1981/1996/2013  
Year(s) Acquired 2006  
Depreciable Lives (Years) [3] -1  
90 Broadway    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 90 Broadway  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 19,104  
Original Building 52,078  
Costs Capitalized Subsequent to Acquisition 17,048  
Land and improvements 20,785  
Buildings and Improvements 67,445  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 88,230  
Accumulated Depreciation $ 17,087  
Year(s) built / renovated 1983/1998/2013  
Year(s) Acquired 2006  
Depreciable Lives (Years) [3] -1  
10 CityPoint    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 10 CityPoint  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 1,953  
Original Building 85,752  
Costs Capitalized Subsequent to Acquisition 163  
Land and improvements 2,116  
Buildings and Improvements 85,752  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 87,868  
Accumulated Depreciation $ 1,601  
Year(s) built / renovated 2016  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
230 CityPoint    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 230 CityPoint  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 13,189  
Original Building 49,823  
Costs Capitalized Subsequent to Acquisition 20,187  
Land and improvements 13,593  
Buildings and Improvements 69,606  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 83,199  
Accumulated Depreciation $ 23,437  
Year(s) built / renovated 1992  
Year(s) Acquired 2005  
Depreciable Lives (Years) [3] -1  
Waltham Weston Corporate Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Waltham Weston Corporate Center  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 10,385  
Original Building 60,694  
Costs Capitalized Subsequent to Acquisition 10,889  
Land and improvements 11,097  
Buildings and Improvements 70,871  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 81,968  
Accumulated Depreciation $ 27,310  
Year(s) built / renovated 2003  
Year(s) Acquired 1999  
Depreciable Lives (Years) [3] -1  
77 CityPoint    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 77 CityPoint  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 13,847  
Original Building 60,383  
Costs Capitalized Subsequent to Acquisition 5,703  
Land and improvements 13,873  
Buildings and Improvements 66,060  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 79,933  
Accumulated Depreciation $ 20,981  
Year(s) built / renovated 2008  
Year(s) Acquired 2001  
Depreciable Lives (Years) [3] -1  
3625-3635 Peterson Way    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 3625-3635 Peterson Way  
Type Office  
Location Santa Clara, CA  
Encumbrances $ 0  
Original Land 63,206  
Original Building 14,879  
Costs Capitalized Subsequent to Acquisition 31  
Land and improvements 63,206  
Buildings and Improvements 14,879  
Land Held for Development 31  
Development and Construction in Progress 0  
Total 78,116  
Accumulated Depreciation $ 2,093  
Year(s) built / renovated 1979  
Year(s) Acquired 2016  
Depreciable Lives (Years) [3] -1  
North First Business Park    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name North First Business Park  
Type Office  
Location San Jose, CA  
Encumbrances $ 0  
Original Land 58,402  
Original Building 13,069  
Costs Capitalized Subsequent to Acquisition 3,932  
Land and improvements 23,377  
Buildings and Improvements 16,116  
Land Held for Development 35,910  
Development and Construction in Progress 0  
Total 75,403  
Accumulated Depreciation $ 15,811  
Year(s) built / renovated 1981  
Year(s) Acquired 2007  
Depreciable Lives (Years) [3] -1  
2440 West El Camino Real    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 2440 West El Camino Real  
Type Office  
Location Mountain View, CA  
Encumbrances $ 0  
Original Land 16,741  
Original Building 51,285  
Costs Capitalized Subsequent to Acquisition 1,814  
Land and improvements 16,741  
Buildings and Improvements 53,099  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 69,840  
Accumulated Depreciation $ 9,817  
Year(s) built / renovated 1987/2003  
Year(s) Acquired 2011  
Depreciable Lives (Years) [3] -1  
300 Binney Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 300 Binney Street  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 18,080  
Original Building 51,262  
Costs Capitalized Subsequent to Acquisition 140  
Land and improvements 18,080  
Buildings and Improvements 51,402  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 69,482  
Accumulated Depreciation $ 6,059  
Year(s) built / renovated 2013  
Year(s) Acquired 2009  
Depreciable Lives (Years) [3] (1)  
Reston Corporate Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Reston Corporate Center  
Type Office  
Location Reston, VA  
Encumbrances $ 0  
Original Land 9,135  
Original Building 50,857  
Costs Capitalized Subsequent to Acquisition 6,256  
Land and improvements 10,148  
Buildings and Improvements 56,100  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 66,248  
Accumulated Depreciation $ 25,244  
Year(s) built / renovated 1984  
Year(s) Acquired 1998  
Depreciable Lives (Years) [3] -1  
Wisconsin Place    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Wisconsin Place  
Type Office  
Location Chevy Chase, MD  
Encumbrances $ 0  
Original Land 0  
Original Building 53,349  
Costs Capitalized Subsequent to Acquisition 9,884  
Land and improvements 0  
Buildings and Improvements 63,233  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 63,233  
Accumulated Depreciation $ 16,406  
Year(s) built / renovated 2009  
Year(s) Acquired 2004  
Depreciable Lives (Years) [3] -1  
New Dominion Technology Park, Bldg. Two    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name New Dominion Technology Park, Bldg. Two  
Type Office  
Location Herndon, VA  
Encumbrances $ 0  
Original Land 5,584  
Original Building 51,868  
Costs Capitalized Subsequent to Acquisition 4,094  
Land and improvements 6,510  
Buildings and Improvements 55,036  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 61,546  
Accumulated Depreciation $ 21,908  
Year(s) built / renovated 2004  
Year(s) Acquired 1998  
Depreciable Lives (Years) [3] -1  
200 West Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 200 West Street  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 16,148  
Original Building 24,983  
Costs Capitalized Subsequent to Acquisition 10,102  
Land and improvements 16,813  
Buildings and Improvements 34,420  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 51,233  
Accumulated Depreciation $ 19,535  
Year(s) built / renovated 1999  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
New Dominion Technology Park, Bldg. One    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name New Dominion Technology Park, Bldg. One  
Type Office  
Location Herndon, VA  
Encumbrances $ 35,485  
Original Land 3,880  
Original Building 43,227  
Costs Capitalized Subsequent to Acquisition 3,883  
Land and improvements 4,583  
Buildings and Improvements 46,407  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 50,990  
Accumulated Depreciation $ 24,362  
Year(s) built / renovated 2001  
Year(s) Acquired 1998  
Depreciable Lives (Years) [3] -1  
Sumner Square    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Sumner Square  
Type Office  
Location Washington, DC  
Encumbrances $ 0  
Original Land 624  
Original Building 28,745  
Costs Capitalized Subsequent to Acquisition 19,428  
Land and improvements 1,478  
Buildings and Improvements 47,319  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 48,797  
Accumulated Depreciation $ 22,237  
Year(s) built / renovated 1985  
Year(s) Acquired 1999  
Depreciable Lives (Years) [3] -1  
University Place    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name University Place  
Type Office  
Location Cambridge, MA  
Encumbrances $ 9,119  
Original Land 0  
Original Building 37,091  
Costs Capitalized Subsequent to Acquisition 9,501  
Land and improvements 390  
Buildings and Improvements 46,202  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 46,592  
Accumulated Depreciation $ 25,207  
Year(s) built / renovated 1985  
Year(s) Acquired 1998  
Depreciable Lives (Years) [3] -1  
2600 Tower Oaks Boulevard    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 2600 Tower Oaks Boulevard  
Type Office  
Location Rockville, MD  
Encumbrances $ 0  
Original Land 4,243  
Original Building 31,125  
Costs Capitalized Subsequent to Acquisition 9,081  
Land and improvements 4,785  
Buildings and Improvements 39,664  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 44,449  
Accumulated Depreciation $ 19,801  
Year(s) built / renovated 2001  
Year(s) Acquired 1998  
Depreciable Lives (Years) [3] -1  
255 Main Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 255 Main Street  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 134  
Original Building 25,110  
Costs Capitalized Subsequent to Acquisition 17,087  
Land and improvements 548  
Buildings and Improvements 41,783  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 42,331  
Accumulated Depreciation $ 27,499  
Year(s) built / renovated 1987  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
Quorum Office Park    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Quorum Office Park  
Type Office  
Location Chelmsford, MA  
Encumbrances $ 0  
Original Land 3,750  
Original Building 32,454  
Costs Capitalized Subsequent to Acquisition 5,813  
Land and improvements 5,187  
Buildings and Improvements 36,830  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 42,017  
Accumulated Depreciation $ 15,633  
Year(s) built / renovated 2001  
Year(s) Acquired 2000  
Depreciable Lives (Years) [3] -1  
500 E Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 500 E Street  
Type Office  
Location Washington, DC  
Encumbrances $ 0  
Original Land 109  
Original Building 22,420  
Costs Capitalized Subsequent to Acquisition 13,219  
Land and improvements 2,379  
Buildings and Improvements 33,369  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 35,748  
Accumulated Depreciation $ 22,987  
Year(s) built / renovated 1987  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
150 Broadway    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 150 Broadway  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 850  
Original Building 25,042  
Costs Capitalized Subsequent to Acquisition 8,623  
Land and improvements 1,323  
Buildings and Improvements 33,192  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 34,515  
Accumulated Depreciation $ 15,545  
Year(s) built / renovated 1999  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
325 Main Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 325 Main Street  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 174  
Original Building 12,200  
Costs Capitalized Subsequent to Acquisition 12,256  
Land and improvements 965  
Buildings and Improvements 23,665  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 24,630  
Accumulated Depreciation $ 12,266  
Year(s) built / renovated 1987/2013  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
105 Broadway    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 105 Broadway  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 1,299  
Original Building 12,943  
Costs Capitalized Subsequent to Acquisition 7,198  
Land and improvements 2,395  
Buildings and Improvements 19,045  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 21,440  
Accumulated Depreciation $ 13,018  
Year(s) built / renovated 1990  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
Lexington Office Park    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Lexington Office Park  
Type Office  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 998  
Original Building 1,426  
Costs Capitalized Subsequent to Acquisition 17,481  
Land and improvements 1,264  
Buildings and Improvements 18,641  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 19,905  
Accumulated Depreciation $ 12,490  
Year(s) built / renovated 1982  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
40 Shattuck Road    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 40 Shattuck Road  
Type Office  
Location Andover, MA  
Encumbrances $ 0  
Original Land 709  
Original Building 14,740  
Costs Capitalized Subsequent to Acquisition 3,368  
Land and improvements 893  
Buildings and Improvements 17,924  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 18,817  
Accumulated Depreciation $ 7,505  
Year(s) built / renovated 2001  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
201 Spring Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 201 Spring Street  
Type Office  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 2,849  
Original Building 15,303  
Costs Capitalized Subsequent to Acquisition 14  
Land and improvements 3,124  
Buildings and Improvements 15,042  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 18,166  
Accumulated Depreciation $ 7,462  
Year(s) built / renovated 1997  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
The Point    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name The Point  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 6,395  
Original Building 10,040  
Costs Capitalized Subsequent to Acquisition 408  
Land and improvements 6,480  
Buildings and Improvements 10,363  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 16,843  
Accumulated Depreciation $ 397  
Year(s) built / renovated 2015  
Year(s) Acquired 2007  
Depreciable Lives (Years) [3] -1  
92-100 Hayden Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 92-100 Hayden Avenue  
Type Office  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 594  
Original Building 6,748  
Costs Capitalized Subsequent to Acquisition 8,181  
Land and improvements 802  
Buildings and Improvements 14,721  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 15,523  
Accumulated Depreciation $ 12,062  
Year(s) built / renovated 1985  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
91 Hartwell Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 91 Hartwell Avenue  
Type Office  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 784  
Original Building 6,464  
Costs Capitalized Subsequent to Acquisition 8,254  
Land and improvements 941  
Buildings and Improvements 14,561  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 15,502  
Accumulated Depreciation $ 9,062  
Year(s) built / renovated 1985  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
690 Folsom Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 690 Folsom Street  
Type Office  
Location San Francisco, CA  
Encumbrances $ 0  
Original Land 3,219  
Original Building 11,038  
Costs Capitalized Subsequent to Acquisition 1,157  
Land and improvements 3,219  
Buildings and Improvements 12,195  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 15,414  
Accumulated Depreciation $ 801  
Year(s) built / renovated 2015  
Year(s) Acquired 2012  
Depreciable Lives (Years) [3] -1  
145 Broadway    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 145 Broadway  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 121  
Original Building 5,535  
Costs Capitalized Subsequent to Acquisition 7,173  
Land and improvements 324  
Buildings and Improvements 10,637  
Land Held for Development 0  
Development and Construction in Progress 1,868  
Total 12,829  
Accumulated Depreciation $ 8,676  
Year(s) built / renovated 1984  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
181 Spring Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 181 Spring Street  
Type Office  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 1,066  
Original Building 9,520  
Costs Capitalized Subsequent to Acquisition 2,195  
Land and improvements 1,160  
Buildings and Improvements 11,621  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 12,781  
Accumulated Depreciation $ 4,876  
Year(s) built / renovated 1999  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
195 West Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 195 West Street  
Type Office  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 1,611  
Original Building 6,652  
Costs Capitalized Subsequent to Acquisition 4,340  
Land and improvements 1,858  
Buildings and Improvements 10,745  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 12,603  
Accumulated Depreciation $ 7,517  
Year(s) built / renovated 1990  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
33 Hayden Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 33 Hayden Avenue  
Type Office  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 266  
Original Building 3,234  
Costs Capitalized Subsequent to Acquisition 8,787  
Land and improvements 425  
Buildings and Improvements 11,862  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 12,287  
Accumulated Depreciation $ 7,612  
Year(s) built / renovated 1979  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
7501 Boston Boulevard, Building Seven    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7501 Boston Boulevard, Building Seven  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 665  
Original Building 9,273  
Costs Capitalized Subsequent to Acquisition 535  
Land and improvements 791  
Buildings and Improvements 9,682  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 10,473  
Accumulated Depreciation $ 4,596  
Year(s) built / renovated 1997  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
7435 Boston Boulevard, Building One    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7435 Boston Boulevard, Building One  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 392  
Original Building 3,822  
Costs Capitalized Subsequent to Acquisition 5,116  
Land and improvements 659  
Buildings and Improvements 8,671  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 9,330  
Accumulated Depreciation $ 6,356  
Year(s) built / renovated 1982  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
250 Binney Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 250 Binney Street  
Type Office  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 110  
Original Building 4,483  
Costs Capitalized Subsequent to Acquisition 3,593  
Land and improvements 273  
Buildings and Improvements 7,913  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 8,186  
Accumulated Depreciation $ 4,684  
Year(s) built / renovated 1983  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
7450 Boston Boulevard, Building Three    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7450 Boston Boulevard, Building Three  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 1,165  
Original Building 4,681  
Costs Capitalized Subsequent to Acquisition 1,807  
Land and improvements 1,430  
Buildings and Improvements 6,223  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 7,653  
Accumulated Depreciation $ 3,321  
Year(s) built / renovated 1987  
Year(s) Acquired 1998  
Depreciable Lives (Years) [3] -1  
8000 Grainger Court, Building Five    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 8000 Grainger Court, Building Five  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 366  
Original Building 4,282  
Costs Capitalized Subsequent to Acquisition 2,607  
Land and improvements 601  
Buildings and Improvements 6,654  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 7,255  
Accumulated Depreciation $ 5,416  
Year(s) built / renovated 1984  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
453 Ravendale Drive    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 453 Ravendale Drive  
Type Office  
Location Mountain View, CA  
Encumbrances $ 0  
Original Land 5,477  
Original Building 1,090  
Costs Capitalized Subsequent to Acquisition 408  
Land and improvements 5,477  
Buildings and Improvements 1,498  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 6,975  
Accumulated Depreciation $ 338  
Year(s) built / renovated 1977  
Year(s) Acquired 2012  
Depreciable Lives (Years) [3] -1  
7500 Boston Boulevard, Building Six    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7500 Boston Boulevard, Building Six  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 138  
Original Building 3,749  
Costs Capitalized Subsequent to Acquisition 2,487  
Land and improvements 406  
Buildings and Improvements 5,968  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 6,374  
Accumulated Depreciation $ 4,538  
Year(s) built / renovated 1985  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
17 Hartwell Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 17 Hartwell Avenue  
Type Office  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 26  
Original Building 150  
Costs Capitalized Subsequent to Acquisition 6,109  
Land and improvements 65  
Buildings and Improvements 6,220  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 6,285  
Accumulated Depreciation $ 552  
Year(s) built / renovated 1968  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
7601 Boston Boulevard, Building Eight    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7601 Boston Boulevard, Building Eight  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 200  
Original Building 878  
Costs Capitalized Subsequent to Acquisition 5,047  
Land and improvements 551  
Buildings and Improvements 5,574  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 6,125  
Accumulated Depreciation $ 4,043  
Year(s) built / renovated 1986  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
7300 Boston Boulevard, Building Thirteen    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7300 Boston Boulevard, Building Thirteen  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 608  
Original Building 4,773  
Costs Capitalized Subsequent to Acquisition 709  
Land and improvements 661  
Buildings and Improvements 5,429  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 6,090  
Accumulated Depreciation $ 5,012  
Year(s) built / renovated 2002  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
8000 Corporate Court, Building Eleven    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 8000 Corporate Court, Building Eleven  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 136  
Original Building 3,071  
Costs Capitalized Subsequent to Acquisition 1,615  
Land and improvements 775  
Buildings and Improvements 4,047  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 4,822  
Accumulated Depreciation $ 2,784  
Year(s) built / renovated 1989  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
7375 Boston Boulevard, Building Ten    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7375 Boston Boulevard, Building Ten  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 23  
Original Building 2,685  
Costs Capitalized Subsequent to Acquisition 912  
Land and improvements 93  
Buildings and Improvements 3,527  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 3,620  
Accumulated Depreciation $ 2,472  
Year(s) built / renovated 1988  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
7374 Boston Boulevard, Building Four    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7374 Boston Boulevard, Building Four  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 241  
Original Building 1,605  
Costs Capitalized Subsequent to Acquisition 1,738  
Land and improvements 398  
Buildings and Improvements 3,186  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 3,584  
Accumulated Depreciation $ 2,452  
Year(s) built / renovated 1984  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
7451 Boston Boulevard, Building Two    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 7451 Boston Boulevard, Building Two  
Type Office  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 249  
Original Building 1,542  
Costs Capitalized Subsequent to Acquisition 1,659  
Land and improvements 613  
Buildings and Improvements 2,837  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 3,450  
Accumulated Depreciation $ 2,330  
Year(s) built / renovated 1982  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
32 Hartwell Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 32 Hartwell Avenue  
Type Office  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 168  
Original Building 1,943  
Costs Capitalized Subsequent to Acquisition 1,012  
Land and improvements 314  
Buildings and Improvements 2,809  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 3,123  
Accumulated Depreciation $ 1,905  
Year(s) built / renovated 1968/1979/1987  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
164 Lexington Road    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 164 Lexington Road  
Type Office  
Location Billerica, MA  
Encumbrances $ 0  
Original Land 592  
Original Building 1,370  
Costs Capitalized Subsequent to Acquisition 319  
Land and improvements 643  
Buildings and Improvements 1,638  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 2,281  
Accumulated Depreciation $ 827  
Year(s) built / renovated 1982  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
The Avant at Reston Town Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name The Avant at Reston Town Center  
Type Residential  
Location Reston, VA  
Encumbrances $ 0  
Original Land 20,350  
Original Building 91,995  
Costs Capitalized Subsequent to Acquisition 815  
Land and improvements 20,350  
Buildings and Improvements 92,810  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 113,160  
Accumulated Depreciation $ 7,306  
Year(s) built / renovated 2014  
Year(s) Acquired 2010  
Depreciable Lives (Years) [3] -1  
The Lofts at Atlantic Wharf    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name The Lofts at Atlantic Wharf  
Type Residential  
Location Boston, MA  
Encumbrances $ 0  
Original Land 3,529  
Original Building 54,891  
Costs Capitalized Subsequent to Acquisition 1,663  
Land and improvements 3,529  
Buildings and Improvements 56,554  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 60,083  
Accumulated Depreciation $ 8,105  
Year(s) built / renovated 2011  
Year(s) Acquired 2007  
Depreciable Lives (Years) [3] -1  
Boston Marriott Cambridge    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Boston Marriott Cambridge  
Type Hotel  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 478  
Original Building 37,918  
Costs Capitalized Subsequent to Acquisition 37,067  
Land and improvements 1,201  
Buildings and Improvements 74,262  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 75,463  
Accumulated Depreciation $ 50,954  
Year(s) built / renovated 1986  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
Kendall Center Green Garage    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Kendall Center Green Garage  
Type Garage  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 0  
Original Building 35,035  
Costs Capitalized Subsequent to Acquisition 7,391  
Land and improvements 103  
Buildings and Improvements 42,323  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 42,426  
Accumulated Depreciation $ 9,334  
Year(s) built / renovated 1984  
Year(s) Acquired 2006  
Depreciable Lives (Years) [3] -1  
Kendall Center Yellow Garage    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Kendall Center Yellow Garage  
Type Garage  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 1,256  
Original Building 15,697  
Costs Capitalized Subsequent to Acquisition 1,571  
Land and improvements 1,434  
Buildings and Improvements 17,090  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 18,524  
Accumulated Depreciation $ 4,723  
Year(s) built / renovated 2006  
Year(s) Acquired 2004  
Depreciable Lives (Years) [3] -1  
Kendall Center Blue Garage    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Kendall Center Blue Garage  
Type Garage  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 1,163  
Original Building 11,633  
Costs Capitalized Subsequent to Acquisition 2,770  
Land and improvements 1,579  
Buildings and Improvements 13,987  
Land Held for Development 0  
Development and Construction in Progress 0  
Total 15,566  
Accumulated Depreciation $ 9,325  
Year(s) built / renovated 1990  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
Salesforce Tower    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Salesforce Tower  
Type Development  
Location San Francisco, CA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 723,866  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 0  
Development and Construction in Progress 723,866  
Total 723,866  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2013  
Depreciable Lives (Years) N/A  
Signature at Reston (formerly Reston Signature Site)    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Signature at Reston (formerly Reston Signature Site)  
Type Development  
Location Reston, VA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 96,444  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 0  
Development and Construction in Progress 96,444  
Total 96,444  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2013  
Depreciable Lives (Years) N/A  
191 Spring Street    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 191 Spring Street  
Type Development  
Location Lexington, MA  
Encumbrances $ 0  
Original Land 2,850  
Original Building 27,166  
Costs Capitalized Subsequent to Acquisition 3,134  
Land and improvements 3,151  
Buildings and Improvements 28,576  
Land Held for Development 0  
Development and Construction in Progress 1,423  
Total 33,150  
Accumulated Depreciation $ 21,660  
Year(s) built / renovated 1971/1995  
Year(s) Acquired 1997  
Depreciable Lives (Years) [3] -1  
Proto at Cambridge (formerly Cambridge Residential / 88 Ames)    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Proto at Cambridge (formerly Cambridge Residential / 88 Ames)  
Type Development  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 24,334  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 0  
Development and Construction in Progress 24,334  
Total 24,334  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2015  
Depreciable Lives (Years) N/A  
Springfield Metro Center    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Springfield Metro Center  
Type Land  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 35,430  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 35,430  
Development and Construction in Progress 0  
Total 35,430  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2007  
Depreciable Lives (Years) N/A  
Tower Oaks Master Plan    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Tower Oaks Master Plan  
Type Land  
Location Rockville, MD  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 29,209  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 29,209  
Development and Construction in Progress 0  
Total 29,209  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 1998  
Depreciable Lives (Years) N/A  
Plaza at Almaden    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Plaza at Almaden  
Type Land  
Location San Jose, CA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 29,081  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 29,081  
Development and Construction in Progress 0  
Total 29,081  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2006  
Depreciable Lives (Years) N/A  
6601 & 6605 Springfield Center Drive    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 6601 & 6605 Springfield Center Drive  
Type Land  
Location Springfield, VA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 13,866  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 13,866  
Development and Construction in Progress 0  
Total 13,866  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2007  
Depreciable Lives (Years) N/A  
214 Third Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 214 Third Avenue  
Type Land  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 13,795  
Land and improvements 0  
Buildings and Improvements 146  
Land Held for Development 13,649  
Development and Construction in Progress 0  
Total 13,795  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2006  
Depreciable Lives (Years) N/A  
103 Fourth Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 103 Fourth Avenue  
Type Land  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 12,052  
Land and improvements 0  
Buildings and Improvements 49  
Land Held for Development 12,003  
Development and Construction in Progress 0  
Total 12,052  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2007  
Depreciable Lives (Years) N/A  
20 CityPoint    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 20 CityPoint  
Type Land  
Location Waltham, MA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 11,666  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 11,666  
Development and Construction in Progress 0  
Total 11,666  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2007  
Depreciable Lives (Years) N/A  
Reston Gateway    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Reston Gateway  
Type Land  
Location Reston, VA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 10,841  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 10,841  
Development and Construction in Progress 0  
Total 10,841  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 1998  
Depreciable Lives (Years) N/A  
Reston Eastgate    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Reston Eastgate  
Type Land  
Location Reston, VA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 9,906  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 9,906  
Development and Construction in Progress 0  
Total 9,906  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2001  
Depreciable Lives (Years) N/A  
Crane Meadow    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Crane Meadow  
Type Land  
Location Marlborough, MA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 8,754  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 8,754  
Development and Construction in Progress 0  
Total 8,754  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2000  
Depreciable Lives (Years) N/A  
Washingtonian North    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Washingtonian North  
Type Land  
Location Gaithersburg, MD  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 7,697  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 7,697  
Development and Construction in Progress 0  
Total 7,697  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 1998  
Depreciable Lives (Years) N/A  
Kendall Center Master Plan    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Kendall Center Master Plan  
Type Land  
Location Cambridge, MA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 4,062  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 4,062  
Development and Construction in Progress 0  
Total 4,062  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired N/A  
Depreciable Lives (Years) N/A  
Fourth and Harrison    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Fourth and Harrison  
Type Land  
Location San Francisco, CA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 3,936  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 3,936  
Development and Construction in Progress 0  
Total 3,936  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired N/A  
Depreciable Lives (Years) N/A  
North First Master Plan    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name North First Master Plan  
Type Land  
Location San Jose, CA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 3,014  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 3,014  
Development and Construction in Progress 0  
Total 3,014  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 2007  
Depreciable Lives (Years) N/A  
Broad Run Business Park    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name Broad Run Business Park  
Type Land  
Location Loudoun County, VA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 2,694  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 2,694  
Development and Construction in Progress 0  
Total 2,694  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 1998  
Depreciable Lives (Years) N/A  
MacArthur Station    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name MacArthur Station  
Type Land  
Location Oakland, CA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 1,316  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 1,316  
Development and Construction in Progress 0  
Total 1,316  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired N/A  
Depreciable Lives (Years) N/A  
30 Shattuck Road    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 30 Shattuck Road  
Type Land  
Location Andover, MA  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 1,214  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 1,214  
Development and Construction in Progress 0  
Total 1,214  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired 1997  
Depreciable Lives (Years) N/A  
2100 Pennsylvania Avenue    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Property Name 2100 Pennsylvania Avenue  
Type Land  
Location Washington, DC  
Encumbrances $ 0  
Original Land 0  
Original Building 0  
Costs Capitalized Subsequent to Acquisition 286  
Land and improvements 0  
Buildings and Improvements 0  
Land Held for Development 286  
Development and Construction in Progress 0  
Total 286  
Accumulated Depreciation $ 0  
Year(s) built / renovated N/A  
Year(s) Acquired N/A  
Depreciable Lives (Years) N/A  
Minimum [Member]    
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]    
Life Used for Depreciation life of the lease  
[1] Includes the unamortized balance of the historical fair value adjustment and unamortized deferred financing costs totaling approximately $33.8 million and $(2.4) million, respectively.
[2] Includes pre-development costs.
[3] Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.