Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands			3 Months Ended
	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of VIEs	9		9
Separate Unrestricted Cash For Deferred Compensation Plan.	$ 37,000	$ 36,100	$ 37,000
Impairment loss			13,615	$ 0
Gains from investments in securities			2,272	1,665
Prepaid expenses and other assets (amounts related to VIEs of $45,672 and $11,824 at March 31, 2024 and December 31, 2023, respectively)	$ 146,286	64,230	$ 146,286
Unconsolidated Joint Ventures [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of VIEs	0		0
Deferred Compensation, Excluding Share-Based Payments and Retirement Benefits
Summary Of Significant Accounting Policies [Line Items]
Gains from investments in securities			$ 2,300	$ 1,700
Shady Grove Innovation District [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment loss	$ 13,600
Environmental Focused Investment Fund
Summary Of Significant Accounting Policies [Line Items]
Prepaid expenses and other assets (amounts related to VIEs of $45,672 and $11,824 at March 31, 2024 and December 31, 2023, respectively)	5,100	$ 4,600	5,100
US Treasury Bill Securities
Summary Of Significant Accounting Policies [Line Items]
U.S. Treasury Bill, Term of Contract		3 months
3-Month United States Treasury Bills	$ 0	$ 302,700	$ 0
Variable Interest Entity, Primary Beneficiary [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of VIEs	9		9
Prepaid expenses and other assets (amounts related to VIEs of $45,672 and $11,824 at March 31, 2024 and December 31, 2023, respectively)	$ 45,672	$ 11,824	$ 45,672
Commercial Real Estate Properties [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of VIEs	5		5