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Significant Accounting Policies - Investment in Commercial Real Estate Properties (Narrative) (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 6 Months Ended
--- | --- | --- | ---
Apr. 30, 2024 | Jun. 30, 2024 | Mar. 31, 2024 | Jun. 30, 2023 | Jun. 30, 2024 | Jun. 30, 2023
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Rental revenue decrease from amortization of acquired leases |  | $ 0.9 |  | $ 6.2 | $ 0.9 | $ 14.5
719 Seventh Avenue |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Write down of value in leasehold interest |  |  | $ 46.3 |  |  |
719 Seventh Avenue | Mathias | Related party |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Proceeds from sale of property | $ 30.5 |  |  |  |  |
760 Madison Avenue |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Write down of value in leasehold interest |  | 13.7 |  |  |  |
Interest capitalized |  | $ 13.2 |  |  |  |
Minimum | Below-Market Leases |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Estimated useful life of other intangible assets (in years) |  | 1 year |  |  | 1 year |
Minimum | Above-Market Leases |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Estimated useful life of other intangible assets (in years) |  | 1 year |  |  | 1 year |
Minimum | In-Place Leases |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Estimated useful life of other intangible assets (in years) |  | 1 year |  |  | 1 year |
Minimum | Building |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Estimated useful life (in years) |  | 3 years |  |  | 3 years |
Maximum | Below-Market Leases |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Estimated useful life of other intangible assets (in years) |  | 15 years |  |  | 15 years |
Maximum | Above-Market Leases |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Estimated useful life of other intangible assets (in years) |  | 15 years |  |  | 15 years |
Maximum | In-Place Leases |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Estimated useful life of other intangible assets (in years) |  | 15 years |  |  | 15 years |
Maximum | Building |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |
Estimated useful life (in years) |  | 40 years |  |  | 40 years |

X
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