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Properties, Net (Details 6) ft² in Thousands, $ in Thousands |  | 9 Months Ended
--- | --- | ---
Jul. 21, 2016 USD ($) Property | Sep. 30, 2016 USD ($) ft² buillding Property | Sep. 30, 2015 USD ($)
Construction and Redevelopment Activities |  |  |
Value of properties contributed |  | $ 22,600 | $ 0
Sale price of land |  | $ 5,700 |
Operating office properties |  |  |
Construction and Redevelopment Activities |  |  |
Square footage of real estate properties (in square feet) | ft² |  | 17,500 |
Number of real estate properties | Property |  | 168 |
Office properties under, or contractually committed for, construction or approved for redevelopment |  |  |
Construction and Redevelopment Activities |  |  |
Square footage of real estate properties (in square feet) | ft² |  | 1,200 |
Number of real estate properties | Property |  | 10 |
Single-tenant data centers | Operating office properties |  |  |
Construction and Redevelopment Activities |  |  |
Transaction Value |  | $ 44,300 |
Ownership percentage sold (percent) | 50.00% |  |
Number of properties contributed | Property | 6 |  |
Value of properties contributed | $ 147,600 |  |
Proceeds from issuance of debt |  | $ 60,000 |
Ownership percentage (percent) | 50.00% |  |
Number of real estate properties | Property |  | 12 |
Newly constructed properties placed in service |  |  |
Construction and Redevelopment Activities |  |  |
Square feet of properties placed in service | ft² |  | 490 |
Number of real estate properties | Property |  | 5 |
Newly redeveloped properties placed in service |  |  |
Construction and Redevelopment Activities |  |  |
Square feet of properties placed in service | ft² |  | 55 |
Number of real estate properties | Property |  | 2 |
Properties under construction or contractually committed for construction |  |  |
Construction and Redevelopment Activities |  |  |
Square footage of real estate properties (in square feet) | ft² |  | 1,100 |
Number of real estate properties | Property |  | 7 |
Properties completed Held-for-future lease | Office properties under, or contractually committed for, construction or approved for redevelopment |  |  |
Construction and Redevelopment Activities |  |  |
Number of real estate properties | Property |  | 2 |
Properties under or approved for redevelopment |  |  |
Construction and Redevelopment Activities |  |  |
Square footage of real estate properties (in square feet) | ft² |  | 104 |
Number of real estate properties | Property |  | 3 |
Operating Properties |  |  |
Construction and Redevelopment Activities |  |  |
Number of Buildings | buillding |  | 15 |
Square footage of real estate properties (in square feet) | ft² |  | 1,126 |
Transaction Value |  | $ 210,713 |
Gain on Disposition |  | 16,179 |
Operating Properties | Data Center Shells | Single-tenant data centers | Operating office properties |  |  |
Construction and Redevelopment Activities |  |  |
Gain on Disposition |  | $ 17,900 |
Number of properties contributed | buillding |  | 6 |
Operating Properties | Regional Office | Arborcrest Corporate Campus |  |  |
Construction and Redevelopment Activities |  |  |
Number of Buildings | buillding |  | 4 |
Square footage of real estate properties (in square feet) | ft² |  | 654 |
Transaction Value |  | $ 142,800 |
Gain on Disposition |  | $ 4,742 |
Operating Properties | Regional Office | 8003 Corporate Drive |  |  |
Construction and Redevelopment Activities |  |  |
Number of Buildings | buillding |  | 1 |
Square footage of real estate properties (in square feet) | ft² |  | 18 |
Transaction Value |  | $ 2,400 |
Gain on Disposition |  | $ 0 |
Operating Properties | Regional Office | 8007, 8013, 8015, 8019 and 8023-8027 Corporate Drive |  |  |
Construction and Redevelopment Activities |  |  |
Number of Buildings | buillding |  | 5 |
Square footage of real estate properties (in square feet) | ft² |  | 130 |
Transaction Value |  | $ 14,513 |
Gain on Disposition |  | $ 1,906 |
Operating Properties | Fort Meade/BW Corridor | 1341 and 1343 Ashton Road |  |  |
Construction and Redevelopment Activities |  |  |
Number of Buildings | buillding |  | 2 |
Square footage of real estate properties (in square feet) | ft² |  | 25 |
Transaction Value |  | $ 2,900 |
Gain on Disposition |  | $ 848 |
Operating Properties | Fort Meade/BW Corridor | 1302, 1304 & 1306 Concourse Drive |  |  |
Construction and Redevelopment Activities |  |  |
Number of Buildings | buillding |  | 3 |
Square footage of real estate properties (in square feet) | ft² |  | 299 |
Transaction Value |  | $ 48,100 |
Gain on Disposition |  | $ 8,683 |

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