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v3.19.3

Segment Information - Real Estate Investments, at Cost of Company's Reportable Segments (Additional Information) (Details) - a | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2019 | Dec. 31, 2018
Assets Held-for-sale | Land Held For Development |  |
Segment Reporting Information [Line Items] |  |
Area of land (in acres) |  | 37.9
3001-3003 and 3025 JFK Boulevard |  |
Segment Reporting Information [Line Items] |  |
Lease agreement term | 99 years | 99 years
Other | Assets Held-for-sale |  |
Segment Reporting Information [Line Items] |  |
Area of land (in acres) | 35.2 |
Other | Assets Held-for-sale | Land Held For Development |  |
Segment Reporting Information [Line Items] |  |
Area of land (in acres) | 35.2 | 35.2
Pennsylvania Suburbs | Assets Held-for-sale | Land Held For Development |  |
Segment Reporting Information [Line Items] |  |
Area of land (in acres) |  | 2.7

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