Notes Payable (Summary Of Indebtedness) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Total notes payable	[1]	$ 3,680,900	$ 3,170,400
Value Of Real Estate Assets At Cost Subject To Secured Notes		2,080,900	0
Unsecured Debt		3,165,924	3,170,367
Secured Debt		514,989	0
Senior Unsecured Notes [Member]
Unsecured Debt		$ 2,784,100	$ 3,130,500
5.31% Term loan Due 2024 | Commercial Banks [Member]
Notes payable, effective interest rate		5.31%	1.85%
Debt Instrument, Maturity Date		Sep. 30, 2024
Unsecured Debt		$ 39,800	$ 39,900
5.20% Term loan, due 2024 | Commercial Banks [Member]
Notes payable, effective interest rate		5.20%
Debt Instrument, Maturity Date		Aug. 29, 2025
Unsecured Debt		$ 300,000	$ 0
3.15% Notes Due 2022 | Senior Unsecured Notes [Member]
Notes payable, effective interest rate		3.15%	3.15%
Debt Instrument, Maturity Date		Dec. 15, 2022
Unsecured Debt		$ 0	$ 349,300
5.07% Notes Due 2023 | Senior Unsecured Notes [Member]
Notes payable, effective interest rate		5.07%	5.07%
Debt Instrument, Maturity Date		Jun. 15, 2023
Unsecured Debt		$ 249,800	$ 249,300
4.36% Notes Due 2024 | Senior Unsecured Notes [Member]
Notes payable, effective interest rate		4.36%	4.36%
Debt Instrument, Maturity Date		Jan. 15, 2024
Unsecured Debt		$ 249,700	$ 249,500
3.68% Notes Due 2024 | Senior Unsecured Notes [Member]
Notes payable, effective interest rate		3.68%	3.68%
Debt Instrument, Maturity Date		Sep. 15, 2024
Unsecured Debt		$ 249,200	$ 248,800
3.74% Notes Due 2028 | Senior Unsecured Notes [Member]
Notes payable, effective interest rate		3.74%	3.74%
Debt Instrument, Maturity Date		Oct. 15, 2028
Unsecured Debt		$ 398,300	$ 397,800
3.67% Notes due 2029 | Senior Unsecured Notes [Member]
Notes payable, effective interest rate		3.67%	3.67%
Debt Instrument, Maturity Date		Jul. 01, 2029
Unsecured Debt	[2]	$ 595,500	$ 594,900
2.91% Notes due 2030 | Senior Unsecured Notes [Member]
Notes payable, effective interest rate		2.91%	2.91%
Debt Instrument, Maturity Date		May 15, 2030
Unsecured Debt		$ 744,800	$ 744,100
3.41% Notes due 2049 | Senior Unsecured Notes [Member]
Notes payable, effective interest rate		3.41%	3.41%
Debt Instrument, Maturity Date		Nov. 01, 2049
Unsecured Debt		$ 296,800	$ 296,800
3.78% - 4.04% Conventional Mortgage Notes, due 2026 - 2028 | Secured Debt [Member]
Secured Debt		$ 291,200	0
3.78% - 4.04% Conventional Mortgage Notes, due 2026 - 2028 | Secured Debt [Member] | Minimum [Member]
Notes payable, effective interest rate		3.78%
Debt Instrument, Maturity Date		Oct. 01, 2026
3.78% - 4.04% Conventional Mortgage Notes, due 2026 - 2028 | Secured Debt [Member] | Maximum [Member]
Notes payable, effective interest rate		4.04%
Debt Instrument, Maturity Date		Apr. 01, 2028
6.16% Variable Rate Notes, due 2026 | Secured Debt [Member]
Notes payable, effective interest rate		6.16%
Secured Debt		$ 166,200	0
6.16% Variable Rate Notes, due 2026 | Secured Debt [Member] | Minimum [Member]
Debt Instrument, Maturity Date		Apr. 01, 2026
6.16% Variable Rate Notes, due 2026 | Secured Debt [Member] | Maximum [Member]
Debt Instrument, Maturity Date		Oct. 01, 2026
6.49% Variable Rate Construction Note, due 2024 | Secured Debt [Member]
Notes payable, effective interest rate		6.49%
Debt Instrument, Maturity Date		Jun. 20, 2024
Secured Debt		$ 18,900	0
3.87% note, due 2028 | Secured Debt [Member]
Notes payable, effective interest rate		3.87%
Debt Instrument, Maturity Date		Jan. 01, 2028
Secured Debt		$ 38,700	0
Unsecured Credit Facility [Member] | Commercial Banks [Member]
Unsecured Debt		$ 42,000	$ 0

[1] Unamortized debt discounts, debt issuance costs, and fair market value adjustments of $18.0 million and $19.6 million are included in senior unsecured notes payable as of December 31, 2022 and 2021, respectively.

[2] The 2029 Notes have an effective annual interest rate of approximately 3.84% through June 2026, which includes the effect of a settled forward interest rate swap, and approximately 3.28% thereafter, for an all-in average effective rate of approximately 3.67%.