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Real Estate Joint Ventures - Narrative (Details) - property | Jun. 30, 2021 | Jun. 02, 2021
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B RE COPT DC JV III LLC |  |
Real Estate [Line Items] |  |
Nominal Ownership % | 10.00% | 10.00%
Disposed of by sale | Data Center Shells in Northern Virginia |  |
Real Estate [Line Items] |  |
Ownership percentage sold |  | 90.00%
Number of real estate properties sold |  | 2

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