XML 94 R79.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Schedule III (Details) | 12 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2015 USD ($) apartment | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($) | Dec. 31, 2015 ft² | Dec. 31, 2015 USD ($) | Dec. 31, 2015 unit | Jun. 30, 2015 ft² | Dec. 31, 2014 USD ($) ft² | Feb. 21, 2014 unit | Dec. 31, 2013 USD ($) ft² | Oct. 02, 2013 unit
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | $ 588,663,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 1,448,929,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 636,299,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 561,256,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 2,112,635,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total |  | $ 2,547,188,000 |  | $ 2,289,509,000 | $ 2,529,131,000 |  | 2,673,891,000 | [2] |  |  | $ 2,547,188,000 |  | $ 2,289,509,000 |
Accumulated Depreciation at December 31, 2011 |  | $ 640,434,000 |  | 611,408,000 | 610,536,000 |  | 692,608,000 |  |  |  | 640,434,000 |  | $ 611,408,000 |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 10,212,000 |  |  |  |  |  |  |  |
Units |  | 506 |  |  |  |  |  |  | 3,258 |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 418,052,000 |  |  |  | $ 417,194,000 |  |  |
Real estate, federal income tax basis |  |  |  |  |  |  | 2,071,600,000 |  |  |  |  |  |  |
Area of land | ft² |  |  |  |  |  | 197,000 |  |  |  |  | 430,000 |  | 1,172,000 |
Development in Process |  |  |  |  |  |  | 36,094,000 |  |  |  | $ 76,235,000 |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, beginning of period |  | $ 2,547,188,000 |  | 2,289,509,000 | 2,529,131,000 |  |  |  |  |  |  |  |  |
Property acquisitions | [4] | 162,702,000 |  | 289,140,000 | 47,444,000 |  |  |  |  |  |  |  |  |
Improvements | [4] | 50,954,000 |  | 98,250,000 | 71,127,000 |  |  |  |  |  |  |  |  |
Impairment write-down |  | (5,909,000) |  | 0 | 0 |  |  |  |  |  |  |  |  |
Write-off of disposed assets |  | (3,291,000) |  | (2,857,000) | (2,017,000) |  |  |  |  |  |  |  |  |
Property sales |  | (77,753,000) |  | (126,854,000) | (356,176,000) |  |  |  |  |  |  |  |  |
Balance, end of period |  | 2,673,891,000 | [2] | 2,547,188,000 | 2,289,509,000 |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, beginning of period |  | 640,434,000 |  | 611,408,000 | 610,536,000 |  |  |  |  |  |  |  |  |
Depreciation |  | 86,536,000 |  | 77,741,000 | 80,510,000 |  |  |  |  |  |  |  |  |
Impairment write-down |  | 0 |  | 0 | 0 |  |  |  |  |  |  |  |  |
Write-off of disposed assets |  | (2,408,000) |  | (2,549,000) | (1,404,000) |  |  |  |  |  |  |  |  |
Property sales |  | (31,954,000) |  | (46,166,000) | (78,234,000) |  |  |  |  |  |  |  |  |
Balance, end of period |  | 692,608,000 |  | $ 640,434,000 | $ 611,408,000 |  |  |  |  |  |  |  |  |
Multifamily Properties [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 125,089,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 297,008,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 235,634,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 112,496,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 545,235,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | 657,731,000 |  |  |  |  | 657,731,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | 141,200,000 |  |  |  |  | 141,200,000 |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 3,014,000 |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | 657,731,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 141,200,000 |  |  |  |  |  |  |  |  |  |  |  |
3801 Connecticut [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 420,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 2,678,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 12,961,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 420,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 15,639,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 16,059,000 |  |  |  |  | 16,059,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 9,901,000 |  |  |  |  | 9,901,000 |  |  |  |  |  |  |
Year of Construction | [5] | Jan. 01, 1951 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [5] | Jan. 01, 1963 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 178,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 307 |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 35,400,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 16,059,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 9,901,000 |  |  |  |  |  |  |  |  |  |  |  |
Roosevelt Towers [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 336,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 1,996,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 11,738,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 336,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 13,734,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 14,070,000 |  |  |  |  | 14,070,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 8,886,000 |  |  |  |  | 8,886,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1964 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | May 01, 1965 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 170,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 191 |  |  |  |  |
Depreciation Life | [6] | 40 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 14,070,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 8,886,000 |  |  |  |  |  |  |  |  |  |  |  |
Park Adams [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 287,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 1,654,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 11,270,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 287,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 12,924,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 13,211,000 |  |  |  |  | 13,211,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 8,901,000 |  |  |  |  | 8,901,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1959 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jan. 01, 1969 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 173,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 200 |  |  |  |  |
Depreciation Life | [6] | 35 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 13,211,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 8,901,000 |  |  |  |  |  |  |  |  |  |  |  |
The Ashby at McLean [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 4,356,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 17,102,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 17,835,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 4,356,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 34,937,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 39,293,000 |  |  |  |  | 39,293,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 22,176,000 |  |  |  |  | 22,176,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1982 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Aug. 01, 1996 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 274,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 256 |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 39,293,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 22,176,000 |  |  |  |  |  |  |  |  |  |  |  |
Walker House Apartments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 2,851,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 7,946,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 7,042,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 2,851,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 14,988,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 17,839,000 |  |  |  |  | 17,839,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 10,197,000 |  |  |  |  | 10,197,000 |  |  |  |  |  |  |
Year of Construction | [5] | Jan. 01, 1971 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [5] | Mar. 01, 1996 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 157,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 212 |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 16,500,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 17,839,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 10,197,000 |  |  |  |  |  |  |  |  |  |  |  |
Bethesda Hill Apartments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 3,900,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 13,412,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 12,733,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 3,900,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 26,145,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 30,045,000 |  |  |  |  | 30,045,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 16,650,000 |  |  |  |  | 16,650,000 |  |  |  |  |  |  |
Year of Construction | [5] | Jan. 01, 1986 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [5] | Nov. 01, 1997 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3],[5] |  |  |  |  | 225,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 195 |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 29,100,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 30,045,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 16,650,000 |  |  |  |  |  |  |  |  |  |  |  |
Bennett Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 2,861,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 917,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 80,036,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 4,774,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 79,040,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 83,814,000 |  |  |  |  | 83,814,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 29,053,000 |  |  |  |  | 29,053,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 2007 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Feb. 01, 2001 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 214,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 224 |  |  |  |  |
Depreciation Life | [6] | 28 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 83,814,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 29,053,000 |  |  |  |  |  |  |  |  |  |  |  |
The Clayborne [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 269,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 0 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 30,754,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 699,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 30,324,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 31,023,000 |  |  |  |  | 31,023,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 12,616,000 |  |  |  |  | 12,616,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 2008 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jun. 01, 2003 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 60,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 74 |  |  |  |  |
Depreciation Life | [6] | 26 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 31,023,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 12,616,000 |  |  |  |  |  |  |  |  |  |  |  |
The Kenmore [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 28,222,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 33,955,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 10,679,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 28,222,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 44,634,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 72,856,000 |  |  |  |  | 72,856,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 10,436,000 |  |  |  |  | 10,436,000 |  |  |  |  |  |  |
Year of Construction | [5] | Jan. 01, 1948 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [5] | Sep. 01, 2008 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 268,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 374 |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 33,600,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 72,856,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 10,436,000 |  |  |  |  |  |  |  |  |  |  |  |
Six Fifty North Glebe Road [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [7] | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 12,787,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[7] |  |  |  |  |  | 0 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [7] |  |  |  |  |  | 37,854,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [7] |  |  |  |  |  | 12,851,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [7] |  |  |  |  |  | 37,790,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[7] | $ 50,641,000 |  |  |  |  | 50,641,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [7] | $ 2,347,000 |  |  |  |  | 2,347,000 |  |  |  |  |  |  |
Year of Construction | [5] | Jan. 01, 2014 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [7] | Jun. 01, 2011 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 139,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 163 |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 32,214,000 |  |  |  | 27,690,000 |  |  |
Development in Process |  |  |  |  |  |  | 1,188,000 |  |  |  | 0 |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[7] | $ 50,641,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [7] | $ 2,347,000 |  |  |  |  |  |  |  |  |  |  |  |
The Paramount [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 8,568,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 38,716,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 1,408,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 8,568,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 40,124,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 48,692,000 |  |  |  |  | 48,692,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 3,894,000 |  |  |  |  | 3,894,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1984 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [5] | Oct. 01, 2013 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 141,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 135 |  |  |  |  | 135
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 48,692,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 3,894,000 |  |  |  |  |  |  |  |  |  |  |  |
Yale West [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 14,684,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 62,069,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 245,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 14,684,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 62,314,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 76,998,000 |  |  |  |  | 76,998,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 4,196,000 |  |  |  |  | 4,196,000 |  |  |  |  |  |  |
Year of Construction | [5] | Jan. 01, 2011 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [5] | Feb. 01, 2014 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3],[5] |  |  |  |  | 173,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 216 |  |  | 216 |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 51,900,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 76,998,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 4,196,000 |  |  |  |  |  |  |  |  |  |  |  |
The Wellington [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 30,548,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 116,563,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 420,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 30,548,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 116,983,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 147,531,000 |  |  |  |  | 147,531,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 1,947,000 |  |  |  |  | 1,947,000 |  |  |  |  |  |  |
Year of Construction | [5] | Jan. 01, 1960 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [5] | Jul. 01, 2015 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3],[5] |  |  |  |  | 842,000 |  |  |  |  |  |  |  |
Units | unit |  |  |  |  |  |  |  |  | 711 |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 147,531,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 1,947,000 |  |  |  |  |  |  |  |  |  |  |  |
The Wellington land parcel [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 0 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 659,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 0 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 15,659,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 15,659,000 |  |  |  |  | 15,659,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 0 |  |  |  |  | 0 |  |  |  |  |  |  |
Date of Acquisition | [5] | Jul. 01, 2015 |  |  |  |  |  |  |  |  |  |  |  |
Development in Process |  |  |  |  |  |  | 15,000,000 | [1],[7] |  |  | $ 15,700,000 |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 15,659,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | 0 |  |  |  |  |  |  |  |  |  |  |  |
Office Buildings [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 342,605,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 902,423,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 328,017,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 328,089,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 1,244,956,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | 1,573,045,000 |  |  |  |  | 1,573,045,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | 437,262,000 |  |  |  |  | 437,262,000 |  |  |  |  |  |  |
Net Rentable Square Feet | ft² | [3] |  |  |  |  | 4,869,000 |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | 1,573,045,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 437,262,000 |  |  |  |  |  |  |  |  |  |  |  |
1901 Pennsylvania Avenue [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 892,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 3,481,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 17,253,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 892,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 20,734,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 21,626,000 |  |  |  |  | 21,626,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 15,589,000 |  |  |  |  | 15,589,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1960 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | May 01, 1977 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 101,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 28 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 21,626,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 15,589,000 |  |  |  |  |  |  |  |  |  |  |  |
51 Monroe Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 840,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 10,869,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 28,634,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 840,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 39,503,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 40,343,000 |  |  |  |  | 40,343,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 29,387,000 |  |  |  |  | 29,387,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1975 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Aug. 01, 1979 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 224,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 41 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 40,343,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 29,387,000 |  |  |  |  |  |  |  |  |  |  |  |
515 King Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 4,102,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 3,931,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 6,022,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 4,102,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 9,953,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 14,055,000 |  |  |  |  | 14,055,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 5,416,000 |  |  |  |  | 5,416,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1966 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jul. 01, 1992 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 75,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 50 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 14,055,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 5,416,000 |  |  |  |  |  |  |  |  |  |  |  |
6110 Executive Boulevard [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 4,621,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 11,926,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 16,383,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 4,621,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 28,309,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 32,930,000 |  |  |  |  | 32,930,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 19,283,000 |  |  |  |  | 19,283,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1971 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jan. 01, 1995 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 203,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 32,930,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 19,283,000 |  |  |  |  |  |  |  |  |  |  |  |
1220 19th Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 7,803,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 11,366,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 15,868,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 7,802,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 27,235,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 35,037,000 |  |  |  |  | 35,037,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 13,982,000 |  |  |  |  | 13,982,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1976 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Nov. 01, 1995 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 104,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 35,037,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 13,982,000 |  |  |  |  |  |  |  |  |  |  |  |
1600 Wilson Boulevard [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 6,661,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 16,742,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 26,685,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 6,661,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 43,427,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 50,088,000 |  |  |  |  | 50,088,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 20,180,000 |  |  |  |  | 20,180,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1973 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Oct. 01, 1997 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 168,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 50,088,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 20,180,000 |  |  |  |  |  |  |  |  |  |  |  |
7900 Westpark Drive [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [8] | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[8] |  |  |  |  |  | 12,049,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 71,825,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [8] |  |  |  |  |  | 84,849,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [8] |  |  |  |  |  | 12,049,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [8] |  |  |  |  |  | 156,674,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[8] | $ 168,723,000 |  |  |  |  | 168,723,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [8] | $ 69,796,000 |  |  |  |  | 69,796,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1972 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Nov. 01, 1997 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 531,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Development in Process |  |  |  |  |  |  | 10,200,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[8] | $ 168,723,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [8] | $ 69,796,000 |  |  |  |  |  |  |  |  |  |  |  |
600 Jefferson Plaza [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 2,296,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 12,188,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 7,040,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 2,296,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 19,228,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 21,524,000 |  |  |  |  | 21,524,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 10,822,000 |  |  |  |  | 10,822,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1985 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | May 01, 1999 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 113,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 21,524,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 10,822,000 |  |  |  |  |  |  |  |  |  |  |  |
Wayne Plaza [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 1,564,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 6,243,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 9,295,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 1,564,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 15,538,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 17,102,000 |  |  |  |  | 17,102,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 8,738,000 |  |  |  |  | 8,738,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1970 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | May 01, 2000 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 99,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 17,102,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 8,738,000 |  |  |  |  |  |  |  |  |  |  |  |
Courthouse Square [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 0 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 17,096,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 8,390,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 0 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 25,486,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 25,486,000 |  |  |  |  | 25,486,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 13,084,000 |  |  |  |  | 13,084,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1979 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Oct. 01, 2000 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 116,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 25,486,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 13,084,000 |  |  |  |  |  |  |  |  |  |  |  |
One Central Plaza [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 5,480,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 39,107,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 17,905,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 5,480,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 57,012,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 62,492,000 |  |  |  |  | 62,492,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 30,982,000 |  |  |  |  | 30,982,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1974 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Apr. 01, 2001 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 267,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 62,492,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 30,982,000 |  |  |  |  |  |  |  |  |  |  |  |
1776 G Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 31,500,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 54,327,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 5,774,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 31,500,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 60,101,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 91,601,000 |  |  |  |  | 91,601,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 27,965,000 |  |  |  |  | 27,965,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1979 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Aug. 01, 2003 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 265,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 91,601,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 27,965,000 |  |  |  |  |  |  |  |  |  |  |  |
Dulles Station II [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [8] | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[8] |  |  |  |  |  | 15,001,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[8] |  |  |  |  |  | 494,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [8] |  |  |  |  |  | (3,400,000) |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [8] |  |  |  |  |  | 484,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [8] |  |  |  |  |  | 11,611,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[8] | $ 12,095,000 |  |  |  |  | 12,095,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [8] | $ 515,000 |  |  |  |  | 515,000 |  |  |  |  |  |  |
Date of Acquisition | [8] | Dec. 01, 2005 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 0 |  |  |  |  |  |  |  |
Area of land | ft² |  |  |  |  |  | 360,000 |  |  |  |  |  |  |  |
Land Placed In Service |  |  |  |  |  |  | 3,600,000 |  |  |  |  |  |  |
Development in Process |  |  |  |  |  |  | 8,500,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[8] | $ 12,095,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [8] | $ 515,000 |  |  |  |  |  |  |  |  |  |  |  |
West Gude Drive [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 11,580,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 43,240,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 12,277,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 11,580,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 55,517,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 67,097,000 |  |  |  |  | 67,097,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 20,184,000 |  |  |  |  | 20,184,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1984 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Aug. 01, 2006 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 277,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 67,097,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 20,184,000 |  |  |  |  |  |  |  |  |  |  |  |
Monument II [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 10,244,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 65,205,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 8,089,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 10,244,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 73,294,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 83,538,000 |  |  |  |  | 83,538,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 22,406,000 |  |  |  |  | 22,406,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 2000 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Mar. 01, 2007 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 208,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 83,538,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 22,406,000 |  |  |  |  |  |  |  |  |  |  |  |
2000 M Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 0 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 61,101,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 21,541,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 0 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 82,642,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 82,642,000 |  |  |  |  | 82,642,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 24,244,000 |  |  |  |  | 24,244,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1971 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Dec. 01, 2007 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 231,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 82,642,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 24,244,000 |  |  |  |  |  |  |  |  |  |  |  |
M Street 2445 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 46,887,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 106,743,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 6,163,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 46,887,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 112,906,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 159,793,000 |  |  |  |  | 159,793,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 31,690,000 |  |  |  |  | 31,690,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1986 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Dec. 01, 2008 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 290,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 100,600,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 159,793,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 31,690,000 |  |  |  |  |  |  |  |  |  |  |  |
Quantico Building E [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 4,518,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 24,801,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 940,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 4,518,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 25,741,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 30,259,000 |  |  |  |  | 30,259,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 7,475,000 |  |  |  |  | 7,475,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 2007 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jun. 01, 2010 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 134,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 30,259,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 7,475,000 |  |  |  |  |  |  |  |  |  |  |  |
Quantico Building G [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 4,897,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 25,376,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | (357,000) |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 4,898,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 25,018,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 29,916,000 |  |  |  |  | 29,916,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 6,824,000 |  |  |  |  | 6,824,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 2009 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jun. 01, 2010 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 136,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 29,916,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 6,824,000 |  |  |  |  |  |  |  |  |  |  |  |
1140 Connecticut Avenue [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 25,226,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 50,495,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 12,102,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 25,226,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 62,597,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 87,823,000 |  |  |  |  | 87,823,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 13,120,000 |  |  |  |  | 13,120,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1966 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jan. 01, 2011 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 183,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 87,823,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 13,120,000 |  |  |  |  |  |  |  |  |  |  |  |
1227 25th Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 17,505,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 21,319,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 2,875,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 17,505,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 24,194,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 41,699,000 |  |  |  |  | 41,699,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 5,696,000 |  |  |  |  | 5,696,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1988 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Mar. 01, 2011 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 135,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 41,699,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 5,696,000 |  |  |  |  |  |  |  |  |  |  |  |
Braddock Place Member |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 18,817,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 71,250,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 10,943,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 18,818,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 82,192,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 101,010,000 |  |  |  |  | 101,010,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 16,263,000 |  |  |  |  | 16,263,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1985 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Sep. 01, 2011 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 350,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 101,010,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 16,263,000 |  |  |  |  |  |  |  |  |  |  |  |
John Marshall II Member |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 13,490,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 53,024,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 2,145,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 13,490,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 55,169,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 68,659,000 |  |  |  |  | 68,659,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 9,531,000 |  |  |  |  | 9,531,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1996 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Sep. 01, 2011 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 223,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 50,100,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 68,659,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 9,531,000 |  |  |  |  |  |  |  |  |  |  |  |
Fairgate at Ballston [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 17,750,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 29,885,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 3,722,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 17,750,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 33,607,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 51,357,000 |  |  |  |  | 51,357,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 5,835,000 |  |  |  |  | 5,835,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1988 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jun. 01, 2012 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 143,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 51,357,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 5,835,000 |  |  |  |  |  |  |  |  |  |  |  |
The Army Navy Club Building [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 30,796,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 39,315,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 1,903,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 30,796,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 41,218,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 72,014,000 |  |  |  |  | 72,014,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 3,831,000 |  |  |  |  | 3,831,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1912 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Mar. 01, 2014 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 108,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 51,000,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 72,014,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 3,831,000 |  |  |  |  |  |  |  |  |  |  |  |
1775 Eye Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 48,086,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 51,074,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 4,976,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 48,086,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 56,050,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 104,136,000 |  |  |  |  | 104,136,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 4,424,000 |  |  |  |  | 4,424,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1964 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | May 01, 2014 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 185,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 104,136,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | 4,424,000 |  |  |  |  |  |  |  |  |  |  |  |
Retail Centers [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 120,969,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 249,498,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 72,648,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 120,671,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 322,444,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | 443,115,000 |  |  |  |  | 443,115,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | 114,146,000 |  |  |  |  | 114,146,000 |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 2,329,000 |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | 443,115,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 114,146,000 |  |  |  |  |  |  |  |  |  |  |  |
Takoma Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 415,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 1,084,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 281,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 415,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 1,365,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 1,780,000 |  |  |  |  | 1,780,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 1,191,000 |  |  |  |  | 1,191,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1962 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jul. 01, 1963 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 51,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 50 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 1,780,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 1,191,000 |  |  |  |  |  |  |  |  |  |  |  |
Westminster [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 519,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 1,775,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 9,802,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 519,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 11,577,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 12,096,000 |  |  |  |  | 12,096,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 7,268,000 |  |  |  |  | 7,268,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1969 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Sep. 01, 1972 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 150,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 37 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 12,096,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 7,268,000 |  |  |  |  |  |  |  |  |  |  |  |
Concord Centre [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 413,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 850,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 5,456,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 413,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 6,306,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 6,719,000 |  |  |  |  | 6,719,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 3,191,000 |  |  |  |  | 3,191,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1960 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Dec. 01, 1973 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 76,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 33 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 6,719,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 3,191,000 |  |  |  |  |  |  |  |  |  |  |  |
Wheaton Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 796,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 857,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 4,665,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 796,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 5,522,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 6,318,000 |  |  |  |  | 6,318,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 3,748,000 |  |  |  |  | 3,748,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1967 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Sep. 01, 1977 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 74,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 50 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 6,318,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 3,748,000 |  |  |  |  |  |  |  |  |  |  |  |
Bradlee [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 4,152,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 5,383,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 10,941,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 4,152,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 16,324,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 20,476,000 |  |  |  |  | 20,476,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 10,793,000 |  |  |  |  | 10,793,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1955 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Dec. 01, 1984 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 171,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 40 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 20,476,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 10,793,000 |  |  |  |  |  |  |  |  |  |  |  |
Chevy Chase Metro Plaza [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 1,549,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 4,304,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 5,539,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 1,549,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 9,843,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 11,392,000 |  |  |  |  | 11,392,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 6,621,000 |  |  |  |  | 6,621,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1975 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Sep. 01, 1985 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 50,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 50 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 11,392,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 6,621,000 |  |  |  |  |  |  |  |  |  |  |  |
Shoppes of Foxchase [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 5,838,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 2,979,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 14,687,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 5,838,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 17,666,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 23,504,000 |  |  |  |  | 23,504,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 6,631,000 |  |  |  |  | 6,631,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1960 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jun. 01, 1994 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 134,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 50 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 23,504,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 6,631,000 |  |  |  |  |  |  |  |  |  |  |  |
Frederick County Square [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 6,561,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 6,830,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 4,782,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 6,561,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 11,612,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 18,173,000 |  |  |  |  | 18,173,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 7,349,000 |  |  |  |  | 7,349,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1973 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Aug. 01, 1995 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 227,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 18,173,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 7,349,000 |  |  |  |  |  |  |  |  |  |  |  |
800 S. Washington Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Virginia |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 2,904,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 5,489,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 5,944,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 2,904,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 11,433,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 14,337,000 |  |  |  |  | 14,337,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 4,761,000 |  |  |  |  | 4,761,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1951 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jun. 01, 1998 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 46,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 14,337,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 4,761,000 |  |  |  |  |  |  |  |  |  |  |  |
Centre at Hagerstown . [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 13,029,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 25,415,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 2,435,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 13,029,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 27,850,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 40,879,000 |  |  |  |  | 40,879,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 12,855,000 |  |  |  |  | 12,855,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 2000 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Jun. 01, 2002 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 332,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 40,879,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 12,855,000 |  |  |  |  |  |  |  |  |  |  |  |
Frederick Crossing [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 12,759,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 35,477,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 2,242,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 12,759,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 37,719,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 50,478,000 |  |  |  |  | 50,478,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 14,430,000 |  |  |  |  | 14,430,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1999 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Mar. 01, 2005 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 295,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 50,478,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 14,430,000 |  |  |  |  |  |  |  |  |  |  |  |
Randolph Shopping Center [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 4,928,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 13,025,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 940,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 4,928,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 13,965,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 18,893,000 |  |  |  |  | 18,893,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 4,785,000 |  |  |  |  | 4,785,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1972 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | May 01, 2006 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 84,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 18,893,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 4,785,000 |  |  |  |  |  |  |  |  |  |  |  |
Montrose Shopping Center [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 11,612,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 22,410,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 1,860,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 11,020,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 24,862,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 35,882,000 |  |  |  |  | 35,882,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 8,490,000 |  |  |  |  | 8,490,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1970 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | May 01, 2006 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 145,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Area of land | ft² |  |  |  |  |  |  |  |  |  | 15,000 |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 35,882,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 8,490,000 |  |  |  |  |  |  |  |  |  |  |  |
Gateway Overlook [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 28,816,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 52,249,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 370,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 29,110,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 52,325,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 81,435,000 |  |  |  |  | 81,435,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 13,734,000 |  |  |  |  | 13,734,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 2007 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Dec. 01, 2010 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 220,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 81,435,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 13,734,000 |  |  |  |  |  |  |  |  |  |  |  |
Olney Village Center Member |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location | [5] | Maryland |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1],[5] |  |  |  |  |  | 15,842,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1],[5] |  |  |  |  |  | 39,133,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition | [5] |  |  |  |  |  | 1,836,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land | [5] |  |  |  |  |  | 15,842,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements | [5] |  |  |  |  |  | 40,969,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2],[5] | $ 56,811,000 |  |  |  |  | 56,811,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 | [5] | $ 6,731,000 |  |  |  |  | 6,731,000 |  |  |  |  |  |  |
Year of Construction | [5] | Jan. 01, 1979 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition | [5] | Aug. 01, 2011 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 199,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Mortgage notes payable |  |  |  |  |  |  | 17,300,000 |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2],[5] | $ 56,811,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [5] | $ 6,731,000 |  |  |  |  |  |  |  |  |  |  |  |
Spring Vally Retail Center [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Location |  | Washington, DC |  |  |  |  |  |  |  |  |  |  |  |
Initial Cost, Land | [1] |  |  |  |  |  | 10,836,000 |  |  |  |  |  |  |
Initial Cost, Buildings and Improvements | [1] |  |  |  |  |  | 32,238,000 |  |  |  |  |  |  |
Net Improvements (Retirement) since Acquisition |  |  |  |  |  |  | 868,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Land |  |  |  |  |  |  | 10,836,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements |  |  |  |  |  |  | 33,106,000 |  |  |  |  |  |  |
Gross Amounts at Which Carried at December 31, 2011, Total | [2] | $ 43,942,000 |  |  |  |  | 43,942,000 |  |  |  |  |  |  |
Accumulated Depreciation at December 31, 2011 |  | $ 1,568,000 |  |  |  |  | $ 1,568,000 |  |  |  |  |  |  |
Year of Construction |  | Jan. 01, 1941 |  |  |  |  |  |  |  |  |  |  |  |
Date of Acquisition |  | Oct. 01, 2014 |  |  |  |  |  |  |  |  |  |  |  |
Net Rentable Square Feet | ft² |  |  |  |  |  | 75,000 |  |  |  |  |  |  |  |
Depreciation Life | [6] | 30 years |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period | [2] | $ 43,942,000 |  |  |  |  |  |  |  |  |  |  |  |
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, end of period |  | $ 1,568,000 |  |  |  |  |  |  |  |  |  |  |  |
Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Useful Life |  | 3 years |  |  |  |  |  |  |  |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Useful Life |  | 50 years |  |  |  |  |  |  |  |  |  |  |  |
[1] | The purchase cost of real estate investments has been divided between land and buildings and improvements on the basis of management’s determination of the fair values.
[2] | At December 31, 2015, total land, buildings and improvements are carried at $2,071.6 million for federal income tax purposes.
[3] | Residential properties are presented in gross square feet.
[4] | Includes non-cash accruals for capital items and assumed mortgages.
[5] | At December 31, 2015, our properties were encumbered by non-recourse mortgage amounts as follows: $35.4 million on 3801 Connecticut Avenue, $16.5 million on Walker House, $29.1 million on Bethesda Hill, $33.6 million million on The Kenmore, $100.6 million on 2445 M Street, $50.1 million on John Marshall II, and $17.3 million on Olney Village Center, $51.9 million on Yale West, and $51.0 million on The Amy Navy Club Building. The Maxwell was encumbered by a construction loan with a 32.2 million million balance at December 31, 2015.
[6] | The useful life shown is for the main structure. Buildings and improvements are depreciated over various useful lives ranging from 3 to 50 years.
[7] | As of December 31, 2015, Washington REIT had under development a multifamily property in Arlington, Virginia. The value not yet placed into service at December 31, 2015 was $15.7 million.
[8] | As of December 31, 2015, Washington REIT had under development an office project with 360,000 square feet of office space and a parking garage to be developed in Herndon, VA (Dulles Station, Phase II). The value not yet placed in service of Dulles Station, Phase II at December 31, 2015 was $8.5 million. $3.6 million of Dulles Station, Phase II was placed into service upon the completion of a portion of the parking garage structure. Additionally, Washington REIT had investments in various development or redevelopment projects, including Silverline Center. The value of this redevelopment not yet placed in service is $10.2 million at December 31, 2015.

X
- Definition Area of a real estate property. + References No definition available. + Details
Name: | us-gaap_AreaOfRealEstateProperty
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition The current amount of expenditures for a real estate project that has not yet been completed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.10) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Phase -URI http://asc.fasb.org/extlink&oid=49177889 + Details
Name: | us-gaap_DevelopmentInProcess
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The number of units in a real estate property owned as of the balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfUnitsInRealEstateProperty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of accumulated depreciation pertaining to real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of other deductions to accumulated depreciation, excluding sales, for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciationOtherDeductions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of decrease to accumulated depreciation for real estate investments sold for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAccumulatedDepreciationRealEstateSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount before accumulated depreciation of buildings and improvements for entities with a substantial portion of business acquiring and holding investment real estate. Excludes real estate not held as an investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of land for entities with a substantial portion of business acquiring and holding investment real estate. Excludes real estate not held as an investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of land and buildings and improvements made to real estate investments and capitalized after acquisition for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Date real estate investment property was acquired for entities with a substantial portion of business acquiring and holding investment real estate, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDateAcquired1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date real estate investment property was constructed for entities with a substantial portion of business acquiring and holding investment real estate, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDateOfConstruction1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Initial cost of buildings and improvements for entities with a substantial portion of business acquiring and holding investment real estate. Excludes real estate not held as an investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Initial cost of land for entities with a substantial portion of business acquiring and holding investment real estate. Excludes real estate not held as an investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Useful life on which depreciation was computed for entities with a substantial portion of business acquiring and holding investment real estate, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationLifeUsedForDepreciation1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of real estate investments sold for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateCostOfRealEstateSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Cost basis of real estate investments for federal income tax purposes for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN6) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateFederalIncomeTaxBasis
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, before accumulated depreciation, of real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateGrossAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase in real estate investments related to improvements for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase in real estate investments from acquisitions other than through foreclosure for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_RealEstateOtherAcquisitions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ReconciliationOfCarryingAmountOfRealEstateInvestmentsRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of depreciation expense of real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 + Details
Name: | us-gaap_SecuredDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Impairment - Gross Asset + References No definition available. + Details
Name: | wre_ImpairmentGrossAsset
Namespace Prefix: | wre_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Land Placed In Service + References No definition available. + Details
Name: | wre_LandPlacedInService
Namespace Prefix: | wre_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Net Rentable Square Feet + References No definition available. + Details
Name: | wre_NetRentableSquareFeet
Namespace Prefix: | wre_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition Real Estate Accumulated Depreciation, Write off of Disposed Assets + References No definition available. + Details
Name: | wre_RealEstateAccumulatedDepreciationWriteOffOfDisposedAssets
Namespace Prefix: | wre_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Real Estate And Accumulated Depreciation Description Of Property Location + References No definition available. + Details
Name: | wre_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyLocation
Namespace Prefix: | wre_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Write Down of Real Estate Disposed Of + References No definition available. + Details
Name: | wre_WriteDownOfRealEstateDisposedOf
Namespace Prefix: | wre_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_MultifamilyPropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A3801ConnecticutMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_RooseveltTowersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_ParkAdamsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_AshbyAtMcleanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_WalkerHouseApartmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_BethesdaHillApartmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_BennettParkMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_ClayborneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_KenmoreMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_SixFiftyNorthGlebeRoadMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_TheParamountMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_YaleWestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_TheWellingtonMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_TheWellingtonlandparcelMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_OfficeBuildingsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A1901PennsylvaniaAvenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A51MonroeStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A515KingStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A6110ExecutiveBoulevardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A122019ThStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A1600WilsonBoulevardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A7900WestparkDriveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A600JeffersonPlazaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_WaynePlazaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_CourthouseSquareMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_OneCentralPlazaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A1776GStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_DullesStationIiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_WestGudeDriveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_MonumentIiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A2000MStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_MStreet2445Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_QuanticoBuildingEMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_QuanticoBuildingGMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A1140ConnecticutAvenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A122725ThStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_BraddockPlaceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_JohnMarshallIiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_FairgateAtBallstonMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_TheArmyNavyClubBuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A1775EyeStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_RetailCentersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_TakomaParkMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_WestminsterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_ConcordCentreMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_WheatonParkMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_BradleeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_ChevyChaseMetroPlazaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_ShoppesOfFoxchaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_FrederickCountySquareMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_A800SWashingtonStreetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_CentreAtHagerstownMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_FrederickCrossingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_RandolphShoppingCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_MontroseShoppingCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_GatewayOverlookMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_OlneyVillageCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=wre_SpringVallyRetailCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |