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Investment in Unconsolidated Joint Ventures (Narrative) (Details) $ in Thousands |  |  |  |  |  |  |  | 3 Months Ended | 6 Months Ended | 59 Months Ended |  |  |
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Jul. 07, 2023 | Jun. 28, 2023 | Jun. 27, 2023 USD ($) | Jun. 02, 2023 | Apr. 21, 2023 ft² Year | Apr. 20, 2023 USD ($) | Jan. 31, 2023 USD ($) ft² a Vehicles Building | Jun. 30, 2023 USD ($) ft² | Jun. 30, 2022 USD ($) | Jun. 30, 2023 USD ($) ft² | Jun. 30, 2022 USD ($) | Jun. 30, 2023 USD ($) ft² | Jun. 05, 2023 USD ($) ft² | Jun. 04, 2023 USD ($) | Dec. 31, 2022 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest and Other Income |  |  |  |  |  |  |  | $ 17,343 | $ 1,195 | $ 28,284 | $ 2,423 |  |  |  |
Related party note receivable |  |  |  |  |  |  |  | $ 88,834 |  | $ 88,834 |  | $ 88,834 |  |  | $ 78,576
3 Hudson Boulevard [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage |  |  |  |  |  |  |  | 25.00% |  | 25.00% |  | 25.00% |  |  |
Interest and Other Income |  |  |  |  |  |  |  |  |  |  |  | $ 23,200 |  |  |
Worldgate Drive | Unconsolidated Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |
Payments to Acquire Interest in Joint Venture |  |  |  |  |  |  | $ 17,000 |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  | 350,000 |  |  |  |  |  |  |  |
Number of buildings | Building |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |
Number of parking space | Vehicles |  |  |  |  |  |  | 1,200 |  |  |  |  |  |  |  |
Area of Land | a |  |  |  |  |  |  | 10 |  |  |  |  |  |  |  |
7750 Wisconsin Avenue [Member] | Unconsolidated Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  | 734,000 |  |  |  |  |  |  |  |  |  |
Construction Loan |  |  |  |  |  | $ 252,600 |  |  |  |  |  |  |  |  |
Debt Instrument, Description of Variable Rate Basis |  |  |  | Term Secured Overnight Finance Rate (“SOFR”) | LIBOR | London interbank offered rate (“LIBOR”) |  |  |  |  |  |  |  |  |
Extension Option (in years) |  |  |  |  | 1 | 1 |  |  |  |  |  |  |  |  |
Number of extensions |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |
7750 Wisconsin Avenue [Member] | Unconsolidated Properties | London Interbank Offered Rate (LIBOR) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  |  |  |  | 1.25% | 1.25% |  |  |  |  |  |  |  |  |
7750 Wisconsin Avenue [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  |  |  | 1.35% |  |  |  |  |  |  |  |  |  |  |
500 North Capitol Street, NW | Unconsolidated Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage |  |  |  |  |  |  |  |  |  |  |  |  | 30.00% |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  |  |  |  |  |  |  | 231,000 |  |
Debt |  |  |  |  |  |  |  |  |  |  |  |  | $ 105,000 | $ 105,000 |
Debt, Weighted Average Interest Rate |  |  |  |  |  |  |  |  |  |  |  |  | 6.83% |  |
500 North Capitol Street, NW | Unconsolidated Properties | Company's Share [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Related party note receivable |  |  |  |  |  |  |  |  |  |  |  |  | $ 10,500 |  |
3 Hudson Boulevard [Member] | Unconsolidated Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Description of Variable Rate Basis |  | LIBOR | LIBOR |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 3.50% | 3.50% |  |  |  |  |  |  |  |  |  |  |  |
Debt |  |  | $ 80,000 |  |  |  |  |  |  |  |  |  |  |  |
Number of extensions |  | 1 | 2 |  |  |  |  |  |  |  |  |  |  |  |
Extension Option (in days) |  |  | 30 days |  |  |  |  |  |  |  |  |  |  |  |
Extension Option Two (in days) |  | 180 days | 180 days |  |  |  |  |  |  |  |  |  |  |  |
3 Hudson Boulevard [Member] | Unconsolidated Properties | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Description of Variable Rate Basis | Term SOFR |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 3.61% |  |  |  |  |  |  |  |  |  |  |  |  |  |
3 Hudson Boulevard [Member] | Unconsolidated Properties | Extended Maturity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Term |  | 30 days |  |  |  |  |  |  |  |  |  |  |  |  |
Platform 16 | Unconsolidated Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage |  |  |  |  |  |  |  | 55.00% |  | 55.00% |  | 55.00% |  |  |
Net Rentable Area (in sf) | ft² |  |  |  |  |  |  |  | 390,000 |  | 390,000 |  | 390,000 |  |  |

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