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Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands |  |  |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | --- | --- | ---
Sep. 30, 2024 USD ($) | Mar. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2023 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2023 USD ($)
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Number of VIEs | 9 |  |  | 9 |  | 9 |
Separate Unrestricted Cash For Deferred Compensation Plan. | $ 38,900 |  | $ 36,100 | $ 38,900 |  | $ 38,900 |
Impairment loss |  |  |  | 0 | $ 0 | 13,615 | $ 0
Unsecured commercial paper | 500,000 |  | 0 | 500,000 |  | 500,000 |
Gains (losses) from investments in securities |  |  |  | 2,198 | (925) | 4,785 | 2,311
Prepaid Expense and Other Assets | $ 132,078 |  | 64,230 | $ 132,078 |  | $ 132,078 |
Unconsolidated Joint Ventures [Member] |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Number of VIEs | 0 |  |  | 0 |  | 0 |
Deferred Compensation, Excluding Share-Based Payments and Retirement Benefits |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Gains (losses) from investments in securities |  |  |  | $ 2,200 | $ (900) | $ 4,800 | $ 2,300
Shady Grove Innovation District [Member] |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Impairment loss |  | $ 13,600 |  |  |  | 13,600 |
Environmental Focused Investment Fund |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Prepaid Expense and Other Assets | $ 6,700 |  | $ 4,600 | 6,700 |  | 6,700 |
US Treasury Bill Securities |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
U.S. Treasury Bill, Term of Contract | 3 months |  | 3 months |  |  |  |
3-Month United States Treasury Bills | $ 175,900 |  | $ 302,700 | $ 175,900 |  | $ 175,900 |
Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Number of VIEs | 9 |  |  | 9 |  | 9 |
Prepaid Expense and Other Assets | $ 50,275 |  | $ 11,824 | $ 50,275 |  | $ 50,275 |
Commercial Real Estate Properties [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |
Number of VIEs | 5 |  |  | 5 |  | 5 |

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