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Schedule III - Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 562,695 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 589,391 |  |  |
Buildings and Improvements | 3,246,749 |  |  |
Net Improvements (Retirements) Since Acquisition | 651,448 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 619,181 |  |  |
Buildings and Improvements | 3,868,407 |  |  |
Total | 4,487,588 | $ 4,631,128 | $ 4,669,289 | $ 4,726,169
Accumulated Depreciation at December 31, 2015 | 1,080,616 | $ 1,078,996 | $ 983,808 | $ 954,665
PENNSYLVANIA SUBURBS [Member] | 400 Berwyn Park [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,657 |  |  |
Buildings and Improvements | 4,462 |  |  |
Net Improvements (Retirements) Since Acquisition | 13,383 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,657 |  |  |
Buildings and Improvements | 17,845 |  |  |
Total | 20,502 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 6,357 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1999 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 300 Berwyn Park [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,206 |  |  |
Buildings and Improvements | 13,422 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,896 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,206 |  |  |
Buildings and Improvements | 17,318 |  |  |
Total | 19,524 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,603 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1050 Westlakes Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,611 |  |  |
Buildings and Improvements | 10,445 |  |  |
Net Improvements (Retirements) Since Acquisition | 5,056 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,611 |  |  |
Buildings and Improvements | 15,501 |  |  |
Total | 18,112 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,686 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1999 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1200 Swedesford Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,595 |  |  |
Buildings and Improvements | 11,809 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,533 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,595 |  |  |
Buildings and Improvements | 15,342 |  |  |
Total | 17,937 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,454 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1994 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 200 Berwyn Park [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,533 |  |  |
Buildings and Improvements | 9,460 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,178 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,533 |  |  |
Buildings and Improvements | 11,638 |  |  |
Total | 13,171 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,846 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1180 Swedesford Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,086 |  |  |
Buildings and Improvements | 8,342 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,978 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,086 |  |  |
Buildings and Improvements | 11,320 |  |  |
Total | 13,406 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,952 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 100 Berwyn Park [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,180 |  |  |
Buildings and Improvements | 7,290 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,948 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,180 |  |  |
Buildings and Improvements | 9,238 |  |  |
Total | 10,418 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,696 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1160 Swedesford Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,781 |  |  |
Buildings and Improvements | 7,124 |  |  |
Net Improvements (Retirements) Since Acquisition | 6,108 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,045 |  |  |
Buildings and Improvements | 12,968 |  |  |
Total | 15,013 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,689 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1100 Cassett Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,695 |  |  |
Buildings and Improvements | 6,779 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,272 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,695 |  |  |
Buildings and Improvements | 8,051 |  |  |
Total | 9,746 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,847 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1997 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 980 Harvest Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,079 |  |  |
Buildings and Improvements | 8,315 |  |  |
Net Improvements (Retirements) Since Acquisition | 149 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,949 |  |  |
Buildings and Improvements | 8,594 |  |  |
Total | 10,543 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,069 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2002 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 910 Harvest Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,225 |  |  |
Buildings and Improvements | 8,645 |  |  |
Net Improvements (Retirements) Since Acquisition | (718) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,225 |  |  |
Buildings and Improvements | 7,927 |  |  |
Total | 9,152 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,822 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 925 Harvest Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,671 |  |  |
Buildings and Improvements | 6,606 |  |  |
Net Improvements (Retirements) Since Acquisition | 913 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,671 |  |  |
Buildings and Improvements | 7,519 |  |  |
Total | 9,190 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,539 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 920 Harvest Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,208 |  |  |
Buildings and Improvements | 6,595 |  |  |
Net Improvements (Retirements) Since Acquisition | (427) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,208 |  |  |
Buildings and Improvements | 6,168 |  |  |
Total | 7,376 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,892 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 181 Washington Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 6,927 |  |  |
Buildings and Improvements | 14,722 |  |  |
Net Improvements (Retirements) Since Acquisition | 318 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 6,237 |  |  |
Buildings and Improvements | 15,730 |  |  |
Total | 21,967 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,215 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2013 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 426 Lancaster Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,689 |  |  |
Buildings and Improvements | 6,756 |  |  |
Net Improvements (Retirements) Since Acquisition | 376 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,689 |  |  |
Buildings and Improvements | 7,132 |  |  |
Total | 8,821 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,621 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 52 Swedesford Square [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,241 |  |  |
Buildings and Improvements | 16,579 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,852 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,241 |  |  |
Buildings and Improvements | 18,431 |  |  |
Total | 22,672 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,115 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | One Progress Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,399 |  |  |
Buildings and Improvements | 5,629 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,802 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,127 |  |  |
Buildings and Improvements | 9,703 |  |  |
Total | 10,830 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,883 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1996 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 500 Enterprise Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,303 |  |  |
Buildings and Improvements | 5,188 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,709 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,303 |  |  |
Buildings and Improvements | 8,897 |  |  |
Total | 10,200 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,624 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1996 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 640 Freedom Business Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,222 |  |  |
Buildings and Improvements | 16,891 |  |  |
Net Improvements (Retirements) Since Acquisition | 4,760 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,222 |  |  |
Buildings and Improvements | 21,651 |  |  |
Total | 25,873 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 10,262 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 555 Croton Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,486 |  |  |
Buildings and Improvements | 17,943 |  |  |
Net Improvements (Retirements) Since Acquisition | (228) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,024 |  |  |
Buildings and Improvements | 18,177 |  |  |
Total | 22,201 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,337 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 630 Allendale Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,836 |  |  |
Buildings and Improvements | 4,028 |  |  |
Net Improvements (Retirements) Since Acquisition | 12,595 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,898 |  |  |
Buildings and Improvements | 16,561 |  |  |
Total | 19,459 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 6,083 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2000 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2000 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 620 Freedom Business Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,770 |  |  |
Buildings and Improvements | 11,014 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,700 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,770 |  |  |
Buildings and Improvements | 14,714 |  |  |
Total | 17,484 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,116 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1000 First Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,772 |  |  |
Buildings and Improvements | 10,936 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,912 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,772 |  |  |
Buildings and Improvements | 12,848 |  |  |
Total | 15,620 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,898 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1980 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1060 First Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,712 |  |  |
Buildings and Improvements | 10,953 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,585 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,712 |  |  |
Buildings and Improvements | 14,538 |  |  |
Total | 17,250 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 6,418 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 630 Freedom Business Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,773 |  |  |
Buildings and Improvements | 11,144 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,991 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,773 |  |  |
Buildings and Improvements | 13,135 |  |  |
Total | 15,908 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 6,403 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1020 First Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,168 |  |  |
Buildings and Improvements | 8,576 |  |  |
Net Improvements (Retirements) Since Acquisition | 7,627 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,168 |  |  |
Buildings and Improvements | 16,203 |  |  |
Total | 18,371 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,618 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1040 First Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,860 |  |  |
Buildings and Improvements | 11,282 |  |  |
Net Improvements (Retirements) Since Acquisition | 5,037 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,860 |  |  |
Buildings and Improvements | 16,319 |  |  |
Total | 19,179 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 6,079 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1985 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 610 Freedom Business Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,017 |  |  |
Buildings and Improvements | 8,070 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,477 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,017 |  |  |
Buildings and Improvements | 10,547 |  |  |
Total | 12,564 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,363 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1985 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 650 Park Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,916 |  |  |
Buildings and Improvements | 4,378 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,655 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,916 |  |  |
Buildings and Improvements | 6,033 |  |  |
Total | 7,949 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,129 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1968 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 500 North Gulph Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,303 |  |  |
Buildings and Improvements | 5,201 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,445 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,303 |  |  |
Buildings and Improvements | 6,646 |  |  |
Total | 7,949 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,577 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1979 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1996 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 620 Allendale Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,020 |  |  |
Buildings and Improvements | 3,839 |  |  |
Net Improvements (Retirements) Since Acquisition | 628 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,020 |  |  |
Buildings and Improvements | 4,467 |  |  |
Total | 5,487 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,132 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1961 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 600 Park Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,012 |  |  |
Buildings and Improvements | 4,048 |  |  |
Net Improvements (Retirements) Since Acquisition | 385 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,012 |  |  |
Buildings and Improvements | 4,433 |  |  |
Total | 5,445 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,166 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1964 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 660 Allendale Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 396 |  |  |
Buildings and Improvements | 948 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,957 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,085 |  |  |
Buildings and Improvements | 3,216 |  |  |
Total | 4,301 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,219 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2011 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 640 Allendale Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 439 |  |  |
Buildings and Improvements | 432 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,507 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 439 |  |  |
Buildings and Improvements | 1,939 |  |  |
Total | 2,378 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 808 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2000 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2000 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 14 Campus Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,244 |  |  |
Buildings and Improvements | 4,217 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,533 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,244 |  |  |
Buildings and Improvements | 5,750 |  |  |
Total | 7,994 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,665 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 17 Campus Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,108 |  |  |
Buildings and Improvements | 5,155 |  |  |
Net Improvements (Retirements) Since Acquisition | (374) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,108 |  |  |
Buildings and Improvements | 4,781 |  |  |
Total | 5,889 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,939 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2001 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 11 Campus Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,112 |  |  |
Buildings and Improvements | 4,067 |  |  |
Net Improvements (Retirements) Since Acquisition | 997 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,112 |  |  |
Buildings and Improvements | 5,064 |  |  |
Total | 6,176 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,116 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1999 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 15 Campus Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,164 |  |  |
Buildings and Improvements | 3,896 |  |  |
Net Improvements (Retirements) Since Acquisition | 247 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,164 |  |  |
Buildings and Improvements | 4,143 |  |  |
Total | 5,307 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,519 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2002 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2000 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 18 Campus Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 787 |  |  |
Buildings and Improvements | 3,312 |  |  |
Net Improvements (Retirements) Since Acquisition | 478 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 787 |  |  |
Buildings and Improvements | 3,790 |  |  |
Total | 4,577 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,649 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1996 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 401 Plymouth Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 6,199 |  |  |
Buildings and Improvements | 16,131 |  |  |
Net Improvements (Retirements) Since Acquisition | 16,709 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 6,199 |  |  |
Buildings and Improvements | 32,840 |  |  |
Total | 39,039 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 11,265 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2001 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2000 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 4000 Chemical Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,373 |  |  |
Buildings and Improvements | 24,546 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,484 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,373 |  |  |
Buildings and Improvements | 26,030 |  |  |
Total | 30,403 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,570 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2006 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 610 West Germantown Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,651 |  |  |
Buildings and Improvements | 14,514 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,375 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,651 |  |  |
Buildings and Improvements | 17,889 |  |  |
Total | 21,540 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 6,508 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2002 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 600 West Germantown Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,652 |  |  |
Buildings and Improvements | 15,288 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,985 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,652 |  |  |
Buildings and Improvements | 17,273 |  |  |
Total | 20,925 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,902 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2002 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 630 West Germantown Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,558 |  |  |
Buildings and Improvements | 14,743 |  |  |
Net Improvements (Retirements) Since Acquisition | 997 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,558 |  |  |
Buildings and Improvements | 15,740 |  |  |
Total | 19,298 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,537 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2002 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 620 West Germantown Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,572 |  |  |
Buildings and Improvements | 14,435 |  |  |
Net Improvements (Retirements) Since Acquisition | 963 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,572 |  |  |
Buildings and Improvements | 15,398 |  |  |
Total | 18,970 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,551 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2002 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 660 West Germantown Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,694 |  |  |
Buildings and Improvements | 5,487 |  |  |
Net Improvements (Retirements) Since Acquisition | 19,418 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 5,405 |  |  |
Buildings and Improvements | 23,194 |  |  |
Total | 28,599 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,357 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2012 |  |  |
Depreciable Life (Years) | 30 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 2240/2250 Butler Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,104 |  |  |
Buildings and Improvements | 4,627 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,312 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,104 |  |  |
Buildings and Improvements | 5,939 |  |  |
Total | 7,043 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,888 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1996 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 2260 Butler Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 662 |  |  |
Buildings and Improvements | 2,727 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,009 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 550 |  |  |
Buildings and Improvements | 4,848 |  |  |
Total | 5,398 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,460 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1996 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 120 West Germantown Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 685 |  |  |
Buildings and Improvements | 2,773 |  |  |
Net Improvements (Retirements) Since Acquisition | 667 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 685 |  |  |
Buildings and Improvements | 3,440 |  |  |
Total | 4,125 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,861 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1996 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 140 West Germantown Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 482 |  |  |
Buildings and Improvements | 1,976 |  |  |
Net Improvements (Retirements) Since Acquisition | 282 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 482 |  |  |
Buildings and Improvements | 2,258 |  |  |
Total | 2,740 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,181 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1996 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 351 Plymouth Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,043 |  |  |
Buildings and Improvements | 555 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,043 |  |  |
Buildings and Improvements | 555 |  |  |
Total | 1,598 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 149 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2000 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 150 Radnor Chester Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 11,925 |  |  |
Buildings and Improvements | 36,986 |  |  |
Net Improvements (Retirements) Since Acquisition | 12,574 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 11,897 |  |  |
Buildings and Improvements | 49,588 |  |  |
Total | 61,485 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 18,681 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1983 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 29 years |  |  |
PENNSYLVANIA SUBURBS [Member] | One Radnor Corporate Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 7,323 |  |  |
Buildings and Improvements | 28,613 |  |  |
Net Improvements (Retirements) Since Acquisition | 23,135 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 7,323 |  |  |
Buildings and Improvements | 51,748 |  |  |
Total | 59,071 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 21,189 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 29 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 201 King of Prussia Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 8,956 |  |  |
Buildings and Improvements | 29,811 |  |  |
Net Improvements (Retirements) Since Acquisition | 4,530 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 8,949 |  |  |
Buildings and Improvements | 34,348 |  |  |
Total | 43,297 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 16,172 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2001 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 25 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 555 Lancaster Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 8,014 |  |  |
Buildings and Improvements | 16,508 |  |  |
Net Improvements (Retirements) Since Acquisition | 16,414 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 8,609 |  |  |
Buildings and Improvements | 32,327 |  |  |
Total | 40,936 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 13,850 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1973 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 24 years |  |  |
PENNSYLVANIA SUBURBS [Member] | Four Radnor Corporate Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 5,406 |  |  |
Buildings and Improvements | 21,390 |  |  |
Net Improvements (Retirements) Since Acquisition | 14,393 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 5,705 |  |  |
Buildings and Improvements | 35,484 |  |  |
Total | 41,189 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 11,578 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1995 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 30 years |  |  |
PENNSYLVANIA SUBURBS [Member] | Five Radnor Corporate Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 6,506 |  |  |
Buildings and Improvements | 25,525 |  |  |
Net Improvements (Retirements) Since Acquisition | 5,512 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 6,578 |  |  |
Buildings and Improvements | 30,965 |  |  |
Total | 37,543 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 9,253 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 38 years |  |  |
PENNSYLVANIA SUBURBS [Member] | Three Radnor Corporate Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,773 |  |  |
Buildings and Improvements | 17,961 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,540 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,791 |  |  |
Buildings and Improvements | 20,483 |  |  |
Total | 25,274 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 9,029 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 29 years |  |  |
PENNSYLVANIA SUBURBS [Member] | Two Radnor Corporate Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,937 |  |  |
Buildings and Improvements | 15,484 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,883 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,942 |  |  |
Buildings and Improvements | 19,362 |  |  |
Total | 23,304 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,797 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 29 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 130 Radnor Chester Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,573 |  |  |
Buildings and Improvements | 8,338 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,483 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,567 |  |  |
Buildings and Improvements | 11,827 |  |  |
Total | 14,394 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,895 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1983 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 25 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 170 Radnor Chester Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,514 |  |  |
Buildings and Improvements | 8,147 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,486 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,509 |  |  |
Buildings and Improvements | 10,638 |  |  |
Total | 13,147 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,488 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1983 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 25 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 200 N. Radnor Chester Rd. [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,366 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,583 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,366 |  |  |
Buildings and Improvements | 3,583 |  |  |
Total | 6,949 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 239 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2014 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2005 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 101 West Elm Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 6,251 |  |  |
Buildings and Improvements | 25,209 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,483 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 6,251 |  |  |
Buildings and Improvements | 28,692 |  |  |
Total | 34,943 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,481 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2005 |  |  |
Depreciable Life (Years) | 40 years |  |  |
PENNSYLVANIA SUBURBS [Member] | 1 West Elm Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,557 |  |  |
Buildings and Improvements | 14,249 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,069 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,557 |  |  |
Buildings and Improvements | 17,318 |  |  |
Total | 20,875 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,089 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2005 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | 2970 Market Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 177,425 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 22,430 |  |  |
Buildings and Improvements | 217,763 |  |  |
Net Improvements (Retirements) Since Acquisition | 25,597 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 22,430 |  |  |
Buildings and Improvements | 243,360 |  |  |
Total | 265,790 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 34,339 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2010 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2007 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | 2929 Arch Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Buildings and Improvements | 208,570 |  |  |
Net Improvements (Retirements) Since Acquisition | 27,724 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 12,586 |  |  |
Buildings and Improvements | 223,708 |  |  |
Total | 236,294 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 93,087 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2005 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | 1717 Arch Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Buildings and Improvements | 98,188 |  |  |
Net Improvements (Retirements) Since Acquisition | 68,523 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 25,195 |  |  |
Buildings and Improvements | 141,516 |  |  |
Total | 166,711 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 26,182 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2010 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | 2001 Market Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 112,000 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 15,323 |  |  |
Buildings and Improvements | 120,200 |  |  |
Net Improvements (Retirements) Since Acquisition | 17,323 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 15,323 |  |  |
Buildings and Improvements | 137,523 |  |  |
Total | 152,846 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,332 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1992 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2013 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | 130 North 18th Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 14,496 |  |  |
Buildings and Improvements | 107,736 |  |  |
Net Improvements (Retirements) Since Acquisition | 27,407 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 14,473 |  |  |
Buildings and Improvements | 135,166 |  |  |
Total | 149,639 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 41,218 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 34 years |  |  |
Philadelphia CBD [Member] | 100 North 18th Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 86,886 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 16,066 |  |  |
Buildings and Improvements | 100,255 |  |  |
Net Improvements (Retirements) Since Acquisition | 12,834 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 16,066 |  |  |
Buildings and Improvements | 113,089 |  |  |
Total | 129,155 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 33,526 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 36 years |  |  |
Philadelphia CBD [Member] | 2005 Market Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 130,000 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 15,161 |  |  |
Buildings and Improvements | 105,021 |  |  |
Net Improvements (Retirements) Since Acquisition | 14,907 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 15,161 |  |  |
Buildings and Improvements | 119,928 |  |  |
Total | 135,089 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 6,783 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2013 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | Cira Centre South Garage [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 35,546 |  |  |
Initial Cost [Abstract] |  |  |  |
Buildings and Improvements | 76,008 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,538 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Buildings and Improvements | 78,546 |  |  |
Total | 78,546 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 10,467 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2010 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | 1900 Market [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 7,768 |  |  |
Buildings and Improvements | 17,263 |  |  |
Net Improvements (Retirements) Since Acquisition | 17,545 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 7,768 |  |  |
Buildings and Improvements | 34,808 |  |  |
Total | 42,576 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,093 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1981 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2012 |  |  |
Depreciable Life (Years) | 30 years |  |  |
Philadelphia CBD [Member] | 3020 Market Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Buildings and Improvements | 21,417 |  |  |
Net Improvements (Retirements) Since Acquisition | 7,975 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Buildings and Improvements | 29,392 |  |  |
Total | 29,392 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,685 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1959 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2011 |  |  |
Depreciable Life (Years) | 26 years |  |  |
Philadelphia CBD [Member] | 101-103 Juniper Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Buildings and Improvements | 14,401 |  |  |
Net Improvements (Retirements) Since Acquisition | 324 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 478 |  |  |
Buildings and Improvements | 14,247 |  |  |
Total | 14,725 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,390 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2010 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | Philadelphia Marine Center [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 532 |  |  |
Buildings and Improvements | 2,196 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,444 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 628 |  |  |
Buildings and Improvements | 5,544 |  |  |
Total | 6,172 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,679 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Philadelphia CBD [Member] | 618-634 Market Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 13,365 |  |  |
Buildings and Improvements | 5,791 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 13,365 |  |  |
Buildings and Improvements | 5,791 |  |  |
Total | 19,156 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 869 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1966 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 5 years |  |  |
Metropolitan DC [Member] | 11720 Beltsville Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,831 |  |  |
Buildings and Improvements | 16,661 |  |  |
Net Improvements (Retirements) Since Acquisition | (5,279) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,927 |  |  |
Buildings and Improvements | 13,286 |  |  |
Total | 15,213 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 6,581 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 46 years |  |  |
Metropolitan DC [Member] | 11700 Beltsville Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,808 |  |  |
Buildings and Improvements | 12,081 |  |  |
Net Improvements (Retirements) Since Acquisition | (10,493) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 336 |  |  |
Buildings and Improvements | 4,060 |  |  |
Total | 4,396 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,963 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1981 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 46 years |  |  |
Metropolitan DC [Member] | 11710 Beltsville Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,278 |  |  |
Buildings and Improvements | 11,100 |  |  |
Net Improvements (Retirements) Since Acquisition | (8,534) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 534 |  |  |
Buildings and Improvements | 4,310 |  |  |
Total | 4,844 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,560 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 46 years |  |  |
Metropolitan DC [Member] | 6600 Rockledge Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Buildings and Improvements | 37,421 |  |  |
Net Improvements (Retirements) Since Acquisition | 10,749 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Buildings and Improvements | 48,170 |  |  |
Total | 48,170 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 10,174 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1981 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 50 years |  |  |
Metropolitan DC [Member] | 11740 Beltsville Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 198 |  |  |
Buildings and Improvements | 870 |  |  |
Net Improvements (Retirements) Since Acquisition | 42 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 202 |  |  |
Buildings and Improvements | 908 |  |  |
Total | 1,110 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 233 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 46 years |  |  |
Metropolitan DC [Member] | 12015 Lee Jackson Memorial Highway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,770 |  |  |
Buildings and Improvements | 22,895 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,902 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,561 |  |  |
Buildings and Improvements | 25,006 |  |  |
Total | 28,567 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,574 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1985 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 42 years |  |  |
Metropolitan DC [Member] | 11781 Lee Jackson Memorial Highway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,246 |  |  |
Buildings and Improvements | 19,836 |  |  |
Net Improvements (Retirements) Since Acquisition | (1,435) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,615 |  |  |
Buildings and Improvements | 19,032 |  |  |
Total | 21,647 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,512 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1982 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Metropolitan DC [Member] | 4401 Fair Lakes Court [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,569 |  |  |
Buildings and Improvements | 11,982 |  |  |
Net Improvements (Retirements) Since Acquisition | (2,098) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 990 |  |  |
Buildings and Improvements | 10,463 |  |  |
Total | 11,453 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,766 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 52 years |  |  |
Metropolitan DC [Member] | 3141 Fairview Park Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 20,838 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 5,918 |  |  |
Buildings and Improvements | 40,981 |  |  |
Net Improvements (Retirements) Since Acquisition | 14,119 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 7,081 |  |  |
Buildings and Improvements | 53,937 |  |  |
Total | 61,018 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 11,640 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 51 years |  |  |
Metropolitan DC [Member] | 2340 Dulles Corner Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 16,345 |  |  |
Buildings and Improvements | 65,379 |  |  |
Net Improvements (Retirements) Since Acquisition | 18,280 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 16,129 |  |  |
Buildings and Improvements | 83,875 |  |  |
Total | 100,004 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 31,570 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Metropolitan DC [Member] | 2291 Wood Oak Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 8,243 |  |  |
Buildings and Improvements | 52,413 |  |  |
Net Improvements (Retirements) Since Acquisition | 12,524 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 8,782 |  |  |
Buildings and Improvements | 64,398 |  |  |
Total | 73,180 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 15,294 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 55 years |  |  |
Metropolitan DC [Member] | 196/198 Van Buren Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 7,931 |  |  |
Buildings and Improvements | 43,812 |  |  |
Net Improvements (Retirements) Since Acquisition | 9,059 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 8,348 |  |  |
Buildings and Improvements | 52,454 |  |  |
Total | 60,802 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 11,986 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 53 years |  |  |
Metropolitan DC [Member] | 2251 Corporate Park Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 11,472 |  |  |
Buildings and Improvements | 45,893 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,367 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 11,472 |  |  |
Buildings and Improvements | 49,260 |  |  |
Total | 60,732 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 11,204 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2000 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Metropolitan DC [Member] | 2355 Dulles Corner Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 10,365 |  |  |
Buildings and Improvements | 43,876 |  |  |
Net Improvements (Retirements) Since Acquisition | 4,612 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 10,365 |  |  |
Buildings and Improvements | 48,488 |  |  |
Total | 58,853 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 13,849 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Metropolitan DC [Member] | 2411 Dulles Corner Park [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 7,279 |  |  |
Buildings and Improvements | 46,340 |  |  |
Net Improvements (Retirements) Since Acquisition | 16,028 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 7,417 |  |  |
Buildings and Improvements | 62,230 |  |  |
Total | 69,647 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 10,822 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 50 years |  |  |
Metropolitan DC [Member] | 13880 Dulles Corner Lane [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 7,236 |  |  |
Buildings and Improvements | 39,213 |  |  |
Net Improvements (Retirements) Since Acquisition | 4,556 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 7,373 |  |  |
Buildings and Improvements | 43,632 |  |  |
Total | 51,005 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 9,193 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1997 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 55 years |  |  |
Metropolitan DC [Member] | 2121 Cooperative Way [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 5,598 |  |  |
Buildings and Improvements | 38,639 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,688 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 5,795 |  |  |
Buildings and Improvements | 41,130 |  |  |
Total | 46,925 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,879 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2000 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 54 years |  |  |
Metropolitan DC [Member] | 2201 Cooperative Way [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,809 |  |  |
Buildings and Improvements | 34,093 |  |  |
Net Improvements (Retirements) Since Acquisition | 5,317 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,809 |  |  |
Buildings and Improvements | 39,410 |  |  |
Total | 44,219 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,573 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 54 years |  |  |
Metropolitan DC [Member] | 13825 Sunrise Valley Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,794 |  |  |
Buildings and Improvements | 19,365 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,126 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,866 |  |  |
Buildings and Improvements | 21,419 |  |  |
Total | 25,285 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,398 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 46 years |  |  |
Metropolitan DC [Member] | 1676 International Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 18,437 |  |  |
Buildings and Improvements | 97,538 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,740 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 18,785 |  |  |
Buildings and Improvements | 100,930 |  |  |
Total | 119,715 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 19,257 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 55 years |  |  |
Metropolitan DC [Member] | 8260 Greensboro Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 7,952 |  |  |
Buildings and Improvements | 33,964 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,227 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 8,102 |  |  |
Buildings and Improvements | 36,041 |  |  |
Total | 44,143 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,898 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1980 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 52 years |  |  |
Metropolitan DC [Member] | 2273 Research Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 5,167 |  |  |
Buildings and Improvements | 31,110 |  |  |
Net Improvements (Retirements) Since Acquisition | 4,638 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 5,237 |  |  |
Buildings and Improvements | 35,678 |  |  |
Total | 40,915 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 10,292 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 45 years |  |  |
Metropolitan DC [Member] | 2275 Research Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 5,059 |  |  |
Buildings and Improvements | 29,668 |  |  |
Net Improvements (Retirements) Since Acquisition | 7,413 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 5,154 |  |  |
Buildings and Improvements | 36,986 |  |  |
Total | 42,140 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 9,057 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 45 years |  |  |
Metropolitan DC [Member] | 2277 Research Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,649 |  |  |
Buildings and Improvements | 26,952 |  |  |
Net Improvements (Retirements) Since Acquisition | 17,817 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,733 |  |  |
Buildings and Improvements | 44,685 |  |  |
Total | 49,418 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,715 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 45 years |  |  |
Metropolitan DC [Member] | 1900 Gallows Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 7,797 |  |  |
Buildings and Improvements | 47,817 |  |  |
Net Improvements (Retirements) Since Acquisition | 11,469 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 7,944 |  |  |
Buildings and Improvements | 59,139 |  |  |
Total | 67,083 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 13,191 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 52 years |  |  |
Metropolitan DC [Member] | 8521 Leesburg Pike [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,316 |  |  |
Buildings and Improvements | 30,885 |  |  |
Net Improvements (Retirements) Since Acquisition | 5,280 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,397 |  |  |
Buildings and Improvements | 36,084 |  |  |
Total | 40,481 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,393 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 51 years |  |  |
New Jersey/ Delaware [Member] | 200 Lake Drive East [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,069 |  |  |
Buildings and Improvements | 8,275 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,798 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,069 |  |  |
Buildings and Improvements | 10,073 |  |  |
Total | 12,142 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,922 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 220 Lake Drive East [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,144 |  |  |
Buildings and Improvements | 8,798 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,955 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,144 |  |  |
Buildings and Improvements | 10,753 |  |  |
Total | 12,897 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,818 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 210 Lake Drive East [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,645 |  |  |
Buildings and Improvements | 6,579 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,748 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,645 |  |  |
Buildings and Improvements | 9,327 |  |  |
Total | 10,972 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,102 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 20 East Clementon Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 769 |  |  |
Buildings and Improvements | 3,055 |  |  |
Net Improvements (Retirements) Since Acquisition | 401 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 769 |  |  |
Buildings and Improvements | 3,456 |  |  |
Total | 4,225 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,712 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 10 Foster Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 244 |  |  |
Buildings and Improvements | 971 |  |  |
Net Improvements (Retirements) Since Acquisition | 78 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 244 |  |  |
Buildings and Improvements | 1,049 |  |  |
Total | 1,293 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 525 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1983 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 7 Foster Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 231 |  |  |
Buildings and Improvements | 921 |  |  |
Net Improvements (Retirements) Since Acquisition | 123 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 231 |  |  |
Buildings and Improvements | 1,044 |  |  |
Total | 1,275 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 514 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1983 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 50 East Clementon Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 114 |  |  |
Buildings and Improvements | 964 |  |  |
Net Improvements (Retirements) Since Acquisition | 671 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 114 |  |  |
Buildings and Improvements | 1,635 |  |  |
Total | 1,749 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 584 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 2 Foster Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 185 |  |  |
Buildings and Improvements | 730 |  |  |
Net Improvements (Retirements) Since Acquisition | 16 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 185 |  |  |
Buildings and Improvements | 746 |  |  |
Total | 931 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 369 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1974 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 4 Foster Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 183 |  |  |
Buildings and Improvements | 726 |  |  |
Net Improvements (Retirements) Since Acquisition | 16 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 183 |  |  |
Buildings and Improvements | 742 |  |  |
Total | 925 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 362 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1974 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 1 Foster Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 93 |  |  |
Buildings and Improvements | 364 |  |  |
Net Improvements (Retirements) Since Acquisition | 57 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 93 |  |  |
Buildings and Improvements | 421 |  |  |
Total | 514 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 228 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1972 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 5 U.S. Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 21 |  |  |
Buildings and Improvements | 81 |  |  |
Net Improvements (Retirements) Since Acquisition | 3 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 21 |  |  |
Buildings and Improvements | 84 |  |  |
Total | 105 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 41 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 5 Foster Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 9 |  |  |
Buildings and Improvements | 32 |  |  |
Net Improvements (Retirements) Since Acquisition | 26 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 9 |  |  |
Buildings and Improvements | 58 |  |  |
Total | 67 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 30 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1968 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | Two Eves Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 818 |  |  |
Buildings and Improvements | 3,461 |  |  |
Net Improvements (Retirements) Since Acquisition | 269 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 818 |  |  |
Buildings and Improvements | 3,730 |  |  |
Total | 4,548 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,761 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | Five Eves Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 703 |  |  |
Buildings and Improvements | 2,819 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,437 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 703 |  |  |
Buildings and Improvements | 4,256 |  |  |
Total | 4,959 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,760 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | Four B Eves Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 588 |  |  |
Buildings and Improvements | 2,369 |  |  |
Net Improvements (Retirements) Since Acquisition | 185 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 588 |  |  |
Buildings and Improvements | 2,554 |  |  |
Total | 3,142 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,311 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | Four A Eves Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 539 |  |  |
Buildings and Improvements | 2,168 |  |  |
Net Improvements (Retirements) Since Acquisition | 376 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 539 |  |  |
Buildings and Improvements | 2,544 |  |  |
Total | 3,083 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,215 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 308 Harper Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,643 |  |  |
Buildings and Improvements | 6,663 |  |  |
Net Improvements (Retirements) Since Acquisition | (39) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,425 |  |  |
Buildings and Improvements | 6,842 |  |  |
Total | 8,267 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,481 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1976 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 1120 Executive Boulevard [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,074 |  |  |
Buildings and Improvements | 8,415 |  |  |
Net Improvements (Retirements) Since Acquisition | 4,280 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,074 |  |  |
Buildings and Improvements | 12,695 |  |  |
Total | 14,769 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,696 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 700 East Gate Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,569 |  |  |
Buildings and Improvements | 14,436 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,956 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,569 |  |  |
Buildings and Improvements | 16,392 |  |  |
Total | 19,961 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,573 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 701 East Gate Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,736 |  |  |
Buildings and Improvements | 6,877 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,163 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,589 |  |  |
Buildings and Improvements | 8,187 |  |  |
Total | 9,776 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,033 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 307 Fellowship Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,565 |  |  |
Buildings and Improvements | 6,342 |  |  |
Net Improvements (Retirements) Since Acquisition | 306 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,330 |  |  |
Buildings and Improvements | 6,883 |  |  |
Total | 8,213 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,551 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1981 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 305 Fellowship Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,421 |  |  |
Buildings and Improvements | 5,768 |  |  |
Net Improvements (Retirements) Since Acquisition | 920 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,233 |  |  |
Buildings and Improvements | 6,876 |  |  |
Total | 8,109 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,340 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1980 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 303 Fellowship Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,493 |  |  |
Buildings and Improvements | 6,055 |  |  |
Net Improvements (Retirements) Since Acquisition | 205 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,250 |  |  |
Buildings and Improvements | 6,503 |  |  |
Total | 7,753 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,213 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1979 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 309 Fellowship Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,518 |  |  |
Buildings and Improvements | 6,154 |  |  |
Net Improvements (Retirements) Since Acquisition | 711 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,518 |  |  |
Buildings and Improvements | 6,865 |  |  |
Total | 8,383 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,206 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1982 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 161 Gaither Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,016 |  |  |
Buildings and Improvements | 4,064 |  |  |
Net Improvements (Retirements) Since Acquisition | 535 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,011 |  |  |
Buildings and Improvements | 4,604 |  |  |
Total | 5,615 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,724 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2001 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 815 East Gate Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 636 |  |  |
Buildings and Improvements | 2,584 |  |  |
Net Improvements (Retirements) Since Acquisition | 446 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 581 |  |  |
Buildings and Improvements | 3,085 |  |  |
Total | 3,666 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,532 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 817 East Gate Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 611 |  |  |
Buildings and Improvements | 2,426 |  |  |
Net Improvements (Retirements) Since Acquisition | 216 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 600 |  |  |
Buildings and Improvements | 2,653 |  |  |
Total | 3,253 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,247 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | Main Street-Plaza 1000 [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,732 |  |  |
Buildings and Improvements | 10,942 |  |  |
Net Improvements (Retirements) Since Acquisition | 96 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,732 |  |  |
Buildings and Improvements | 11,038 |  |  |
Total | 13,770 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 11,002 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | Main Street-Piazza [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 696 |  |  |
Buildings and Improvements | 2,802 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,360 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 696 |  |  |
Buildings and Improvements | 6,162 |  |  |
Total | 6,858 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,035 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1990 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | Main Street-Promenade [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 532 |  |  |
Buildings and Improvements | 2,052 |  |  |
Net Improvements (Retirements) Since Acquisition | 538 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 532 |  |  |
Buildings and Improvements | 2,590 |  |  |
Total | 3,122 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,288 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1997 |  |  |
Depreciable Life (Years) | 40 years |  |  |
New Jersey/ Delaware [Member] | 920 North King Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 6,141 |  |  |
Buildings and Improvements | 21,140 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,707 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 6,141 |  |  |
Buildings and Improvements | 23,847 |  |  |
Total | 29,988 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,113 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 30 years |  |  |
New Jersey/ Delaware [Member] | 300 Delaware Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 6,369 |  |  |
Buildings and Improvements | 13,739 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,889 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 6,369 |  |  |
Buildings and Improvements | 16,628 |  |  |
Total | 22,997 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 7,496 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2004 |  |  |
Depreciable Life (Years) | 23 years |  |  |
Austin, Texas [Member] | 11501 Burnet Road - Building 1 [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,755 |  |  |
Buildings and Improvements | 22,702 |  |  |
Net Improvements (Retirements) Since Acquisition | 119 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,755 |  |  |
Buildings and Improvements | 22,821 |  |  |
Total | 26,576 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 358 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 35 years |  |  |
Austin, Texas [Member] | 11501 Burnet Road - Building 2 [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,732 |  |  |
Buildings and Improvements | 16,305 |  |  |
Net Improvements (Retirements) Since Acquisition | 654 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,732 |  |  |
Buildings and Improvements | 16,959 |  |  |
Total | 19,691 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 274 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 35 years |  |  |
Austin, Texas [Member] | 11501 Burnet Road - Building 3 [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,688 |  |  |
Buildings and Improvements | 22,348 |  |  |
Net Improvements (Retirements) Since Acquisition | 118 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,688 |  |  |
Buildings and Improvements | 22,466 |  |  |
Total | 26,154 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 353 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 35 years |  |  |
Austin, Texas [Member] | 11501 Burnet Road - Building 4 [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,614 |  |  |
Buildings and Improvements | 15,740 |  |  |
Net Improvements (Retirements) Since Acquisition | 83 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,614 |  |  |
Buildings and Improvements | 15,823 |  |  |
Total | 18,437 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 248 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 35 years |  |  |
Austin, Texas [Member] | 11501 Burnet Road - Building 5 [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 3,689 |  |  |
Buildings and Improvements | 22,354 |  |  |
Net Improvements (Retirements) Since Acquisition | 117 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,689 |  |  |
Buildings and Improvements | 22,471 |  |  |
Total | 26,160 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 353 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 35 years |  |  |
Austin, Texas [Member] | 11501 Burnet Road - Building 6 [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,676 |  |  |
Buildings and Improvements | 15,972 |  |  |
Net Improvements (Retirements) Since Acquisition | 84 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,676 |  |  |
Buildings and Improvements | 16,056 |  |  |
Total | 18,732 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 252 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 35 years |  |  |
Austin, Texas [Member] | 11501 Burnet Road - Building 8 [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,400 |  |  |
Buildings and Improvements | 7,422 |  |  |
Net Improvements (Retirements) Since Acquisition | 39 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,400 |  |  |
Buildings and Improvements | 7,461 |  |  |
Total | 8,861 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 122 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 35 years |  |  |
Austin, Texas [Member] | 11501 Burnet Road - Parking Garage [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Buildings and Improvements | 19,826 |  |  |
Net Improvements (Retirements) Since Acquisition | 103 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Buildings and Improvements | 19,929 |  |  |
Total | 19,929 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 424 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2015 |  |  |
Depreciable Life (Years) | 35 years |  |  |
Richmond, Virginia [Member] | 4364 South Alston Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,622 |  |  |
Buildings and Improvements | 6,419 |  |  |
Net Improvements (Retirements) Since Acquisition | (454) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,144 |  |  |
Buildings and Improvements | 6,443 |  |  |
Total | 7,587 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,512 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1985 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 4805 Lake Brooke Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,640 |  |  |
Buildings and Improvements | 6,567 |  |  |
Net Improvements (Retirements) Since Acquisition | 703 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,420 |  |  |
Buildings and Improvements | 7,490 |  |  |
Total | 8,910 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,576 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1996 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | Overlook I [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 748 |  |  |
Buildings and Improvements | 3,976 |  |  |
Net Improvements (Retirements) Since Acquisition | 600 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 791 |  |  |
Buildings and Improvements | 4,533 |  |  |
Total | 5,324 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 916 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2011 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | Overlook II [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 748 |  |  |
Buildings and Improvements | 4,492 |  |  |
Net Improvements (Retirements) Since Acquisition | 504 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 791 |  |  |
Buildings and Improvements | 4,953 |  |  |
Total | 5,744 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 923 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2000 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2011 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2812 Emerywood Parkway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,069 |  |  |
Buildings and Improvements | 4,281 |  |  |
Net Improvements (Retirements) Since Acquisition | 670 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,069 |  |  |
Buildings and Improvements | 4,951 |  |  |
Total | 6,020 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,290 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1980 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 300 Arboretum Place [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 5,450 |  |  |
Buildings and Improvements | 21,892 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,831 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,674 |  |  |
Buildings and Improvements | 26,499 |  |  |
Total | 31,173 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 12,104 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 7501 Boulders View Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,669 |  |  |
Buildings and Improvements | 19,699 |  |  |
Net Improvements (Retirements) Since Acquisition | (2,770) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,920 |  |  |
Buildings and Improvements | 17,678 |  |  |
Total | 21,598 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,891 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2007 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 7300 Beaufont Springs Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,672 |  |  |
Buildings and Improvements | 19,689 |  |  |
Net Improvements (Retirements) Since Acquisition | (1,080) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,980 |  |  |
Buildings and Improvements | 19,301 |  |  |
Total | 23,281 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,999 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2000 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2007 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 6800 Paragon Place [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,552 |  |  |
Buildings and Improvements | 18,414 |  |  |
Net Improvements (Retirements) Since Acquisition | (681) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 3,821 |  |  |
Buildings and Improvements | 18,464 |  |  |
Total | 22,285 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,456 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 6802 Paragon Place [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,917 |  |  |
Buildings and Improvements | 11,454 |  |  |
Net Improvements (Retirements) Since Acquisition | 3,074 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,917 |  |  |
Buildings and Improvements | 14,528 |  |  |
Total | 17,445 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,706 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2002 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 1025 Boulders Parkway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,574 |  |  |
Buildings and Improvements | 11,297 |  |  |
Net Improvements (Retirements) Since Acquisition | (1,314) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,040 |  |  |
Buildings and Improvements | 10,517 |  |  |
Total | 12,557 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,009 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1994 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2007 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2100-2116 West Laburnam Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,482 |  |  |
Buildings and Improvements | 8,846 |  |  |
Net Improvements (Retirements) Since Acquisition | 2,742 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,482 |  |  |
Buildings and Improvements | 11,588 |  |  |
Total | 14,070 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 5,331 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 7401 Beaufont Springs Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,349 |  |  |
Buildings and Improvements | 10,396 |  |  |
Net Improvements (Retirements) Since Acquisition | (2,048) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,788 |  |  |
Buildings and Improvements | 8,909 |  |  |
Total | 10,697 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,649 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1998 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2007 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 7325 Beaufont Springs Drive [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 2,344 |  |  |
Buildings and Improvements | 10,377 |  |  |
Net Improvements (Retirements) Since Acquisition | (1,745) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 2,002 |  |  |
Buildings and Improvements | 8,974 |  |  |
Total | 10,976 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,349 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1999 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2007 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 9011 Arboretum Parkway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,857 |  |  |
Buildings and Improvements | 7,702 |  |  |
Net Improvements (Retirements) Since Acquisition | (430) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,501 |  |  |
Buildings and Improvements | 7,628 |  |  |
Total | 9,129 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 4,104 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 6806 Paragon Place [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Buildings and Improvements | 10,288 |  |  |
Net Improvements (Retirements) Since Acquisition | (117) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 403 |  |  |
Buildings and Improvements | 9,768 |  |  |
Total | 10,171 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,885 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 2007 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2005 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 9100 Arboretum Parkway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,362 |  |  |
Buildings and Improvements | 5,489 |  |  |
Net Improvements (Retirements) Since Acquisition | 541 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,274 |  |  |
Buildings and Improvements | 6,118 |  |  |
Total | 7,392 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,974 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2511 Brittons Hill Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,202 |  |  |
Buildings and Improvements | 4,820 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,221 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,202 |  |  |
Buildings and Improvements | 6,041 |  |  |
Total | 7,243 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3,041 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 9200 Arboretum Parkway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 985 |  |  |
Buildings and Improvements | 3,973 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,275 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 985 |  |  |
Buildings and Improvements | 5,248 |  |  |
Total | 6,233 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,562 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 9210 Arboretum Parkway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,110 |  |  |
Buildings and Improvements | 4,474 |  |  |
Net Improvements (Retirements) Since Acquisition | 167 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 970 |  |  |
Buildings and Improvements | 4,781 |  |  |
Total | 5,751 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,274 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2201-2245 Tomlynn Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,020 |  |  |
Buildings and Improvements | 4,067 |  |  |
Net Improvements (Retirements) Since Acquisition | 1,126 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,020 |  |  |
Buildings and Improvements | 5,193 |  |  |
Total | 6,213 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 2,332 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 9211 Arboretum Parkway [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 582 |  |  |
Buildings and Improvements | 2,433 |  |  |
Net Improvements (Retirements) Since Acquisition | 317 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 470 |  |  |
Buildings and Improvements | 2,862 |  |  |
Total | 3,332 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,395 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1991 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2221-2245 Dabney Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 530 |  |  |
Buildings and Improvements | 2,123 |  |  |
Net Improvements (Retirements) Since Acquisition | 369 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 530 |  |  |
Buildings and Improvements | 2,492 |  |  |
Total | 3,022 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,091 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1994 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2212-2224 Tomlynn Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 502 |  |  |
Buildings and Improvements | 2,014 |  |  |
Net Improvements (Retirements) Since Acquisition | 487 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 502 |  |  |
Buildings and Improvements | 2,501 |  |  |
Total | 3,003 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,109 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1985 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2244 Dabney Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 550 |  |  |
Buildings and Improvements | 2,203 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 550 |  |  |
Buildings and Improvements | 2,203 |  |  |
Total | 2,753 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,016 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1993 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2277 Dabney Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 507 |  |  |
Buildings and Improvements | 2,034 |  |  |
Net Improvements (Retirements) Since Acquisition | 294 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 507 |  |  |
Buildings and Improvements | 2,328 |  |  |
Total | 2,835 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,077 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1986 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2248 Dabney Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 512 |  |  |
Buildings and Improvements | 2,049 |  |  |
Net Improvements (Retirements) Since Acquisition | 379 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 503 |  |  |
Buildings and Improvements | 2,437 |  |  |
Total | 2,940 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 1,000 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1989 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2161-2179 Tomlynn Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 423 |  |  |
Buildings and Improvements | 1,695 |  |  |
Net Improvements (Retirements) Since Acquisition | 306 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 423 |  |  |
Buildings and Improvements | 2,001 |  |  |
Total | 2,424 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 867 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1985 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2246 Dabney Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 455 |  |  |
Buildings and Improvements | 1,822 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 455 |  |  |
Buildings and Improvements | 1,822 |  |  |
Total | 2,277 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 841 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1987 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2251 Dabney Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 387 |  |  |
Buildings and Improvements | 1,552 |  |  |
Net Improvements (Retirements) Since Acquisition | 59 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 387 |  |  |
Buildings and Improvements | 1,611 |  |  |
Total | 1,998 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 740 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1983 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2256 Dabney Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 356 |  |  |
Buildings and Improvements | 1,427 |  |  |
Net Improvements (Retirements) Since Acquisition | 225 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 356 |  |  |
Buildings and Improvements | 1,652 |  |  |
Total | 2,008 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 777 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1982 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2130-2146 Tomlynn Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 353 |  |  |
Buildings and Improvements | 1,416 |  |  |
Net Improvements (Retirements) Since Acquisition | 225 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 353 |  |  |
Buildings and Improvements | 1,641 |  |  |
Total | 1,994 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 779 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1988 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2112-2124 Tomlynn Street [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 281 |  |  |
Buildings and Improvements | 1,125 |  |  |
Net Improvements (Retirements) Since Acquisition | 306 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 281 |  |  |
Buildings and Improvements | 1,431 |  |  |
Total | 1,712 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 695 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | 2240 Dabney Road [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 264 |  |  |
Buildings and Improvements | 1,059 |  |  |
Net Improvements (Retirements) Since Acquisition | 88 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 264 |  |  |
Buildings and Improvements | 1,147 |  |  |
Total | 1,411 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 514 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 1998 |  |  |
Depreciable Life (Years) | 40 years |  |  |
Richmond, Virginia [Member] | Boulders Land [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 1,256 |  |  |
Net Improvements (Retirements) Since Acquisition | (116) |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 1,115 |  |  |
Buildings and Improvements | 25 |  |  |
Total | 1,140 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 3 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2007 |  |  |
California [Member] | 1200 Concord Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 6,395 |  |  |
Buildings and Improvements | 24,664 |  |  |
Net Improvements (Retirements) Since Acquisition | 833 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 6,515 |  |  |
Buildings and Improvements | 25,377 |  |  |
Total | 31,892 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 9,192 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 34 years |  |  |
California [Member] | 1220 Concord Avenue [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 6,476 |  |  |
Buildings and Improvements | 24,966 |  |  |
Net Improvements (Retirements) Since Acquisition | 298 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 6,476 |  |  |
Buildings and Improvements | 25,264 |  |  |
Total | 31,740 |  |  |
Accumulated Depreciation at December 31, 2015 | $ 8,869 |  |  |
Real Estate And Accumulated Depreciation Construction Year | 1984 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |
Depreciable Life (Years) | 34 years |  |  |
California [Member] | Oakland Lot B [Member] |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |
Encumbrances | $ 0 |  |  |
Initial Cost [Abstract] |  |  |  |
Land | 4,342 |  |  |
Net Improvements (Retirements) Since Acquisition | 17 |  |  |
Carrying Amount at Which Carried [Abstract] |  |  |  |
Land | 4,332 |  |  |
Buildings and Improvements | 27 |  |  |
Total | $ 4,359 |  |  |
Real Estate And Accumulated Depreciation Year Of Acquisition | 2006 |  |  |

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