Detail of secured and unsecured debt (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Debt Instrument
Effective rate (as a percent)	3.27%
Future principal payments due on secured and unsecured debt
2021	$ 870
2022	3,592
2023	3,772
2024	183,559
2025	600,034
Thereafter	8,525,554
Outstanding Balance	9,317,381
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(53,794)
Total Consolidated	$ 9,263,587
Secured notes payable
Debt Instrument
Stated interest rate (as a percent)	4.83%
Effective rate (as a percent)	3.41%
Future principal payments due on secured and unsecured debt
2021	$ 870
2022	3,592
2023	3,772
2024	183,559
2025	34
Thereafter	554
Outstanding Balance	192,381
Unamortized (Deferred Financing Cost), (Discount)/ Premium	6,377
Total Consolidated	$ 198,758
Secured Notes Payable Maturing on 2/6/24
Debt Instrument
Stated interest rate (as a percent)	4.82%
Effective rate (as a percent)	3.40%
Maturity Date	Feb. 06, 2024
Future principal payments due on secured and unsecured debt
2021	$ 870
2022	3,564
2023	3,742
2024	183,527
2025	0
Thereafter	0
Outstanding Balance	191,703
Unamortized (Deferred Financing Cost), (Discount)/ Premium	6,377
Total Consolidated	$ 198,080
Secured Notes Payable Maturing on 7/1/36
Debt Instrument
Stated interest rate (as a percent)	6.50%
Effective rate (as a percent)	6.50%
Maturity Date	Jul. 01, 2036
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	28
2023	30
2024	32
2025	34
Thereafter	554
Outstanding Balance	678
Unamortized (Deferred Financing Cost), (Discount)/ Premium	0
Total Consolidated	$ 678
Unsecured Debt
Debt Instrument
Effective rate (as a percent)	3.27%
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	600,000
Thereafter	8,525,000
Outstanding Balance	9,125,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(60,171)
Total Consolidated	$ 9,064,829
Unsecured senior lines of credit
Debt Instrument
Maturity Date	Jan. 06, 2026
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	0
Outstanding Balance	0
Unamortized (Deferred Financing Cost), (Discount)/ Premium	0
Total Consolidated	$ 0
3.45% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	3.45%
Effective rate (as a percent)	3.62%
Maturity Date	Apr. 30, 2025
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	600,000
Thereafter	0
Outstanding Balance	600,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(3,151)
Total Consolidated	$ 596,849
4.30% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	4.30%
Effective rate (as a percent)	4.50%
Maturity Date	Jan. 15, 2026
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	300,000
Outstanding Balance	300,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(2,106)
Total Consolidated	$ 297,894
3.80% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	3.80%
Effective rate (as a percent)	3.96%
Maturity Date	Apr. 15, 2026
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	350,000
Outstanding Balance	350,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(2,237)
Total Consolidated	$ 347,763
3.95% Unsecured Senior Notes Payable Due in 2027
Debt Instrument
Stated interest rate (as a percent)	3.95%
Effective rate (as a percent)	4.13%
Maturity Date	Jan. 15, 2027
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	350,000
Outstanding Balance	350,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(2,693)
Total Consolidated	$ 347,307
3.95% Unsecured Senior Notes Payable Due in 2028
Debt Instrument
Stated interest rate (as a percent)	3.95%
Effective rate (as a percent)	4.07%
Maturity Date	Jan. 15, 2028
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	425,000
Outstanding Balance	425,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(2,673)
Total Consolidated	$ 422,327
4.50% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	4.50%
Effective rate (as a percent)	4.60%
Maturity Date	Jul. 30, 2029
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	300,000
Outstanding Balance	300,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(1,744)
Total Consolidated	$ 298,256
2.75% Unsecured Senior Notes Payable Due 2029
Debt Instrument
Stated interest rate (as a percent)	2.75%
Effective rate (as a percent)	2.87%
Maturity Date	Dec. 15, 2029
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	400,000
Outstanding Balance	400,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(3,385)
Total Consolidated	$ 396,615
4.70% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	4.70%
Effective rate (as a percent)	4.81%
Maturity Date	Jul. 01, 2030
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	450,000
Outstanding Balance	450,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(3,259)
Total Consolidated	$ 446,741
4.90% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	4.90%
Effective rate (as a percent)	5.05%
Maturity Date	Dec. 15, 2030
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	700,000
Outstanding Balance	700,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(7,261)
Total Consolidated	$ 692,739
3.375% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	3.375%
Effective rate (as a percent)	3.48%
Maturity Date	Aug. 15, 2031
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	750,000
Outstanding Balance	750,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(6,422)
Total Consolidated	$ 743,578
2.00% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	2.00%
Effective rate (as a percent)	2.12%
Maturity Date	May 18, 2032
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	900,000
Outstanding Balance	900,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(9,939)
Total Consolidated	$ 890,061
1.875% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	1.875%
Effective rate (as a percent)	1.97%
Maturity Date	Feb. 01, 2033
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	1,000,000
Outstanding Balance	1,000,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(9,916)
Total Consolidated	$ 990,084
4.85% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	4.85%
Effective rate (as a percent)	4.93%
Maturity Date	Apr. 15, 2049
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	300,000
Outstanding Balance	300,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(3,246)
Total Consolidated	$ 296,754
4.00% Unsecured Senior Notes Payables Due 2050
Debt Instrument
Stated interest rate (as a percent)	4.00%
Effective rate (as a percent)	3.91%
Maturity Date	Feb. 01, 2050
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	700,000
Outstanding Balance	700,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	10,342
Total Consolidated	$ 710,342
3.00% Unsecured Senior Notes Payable
Debt Instrument
Stated interest rate (as a percent)	3.00%
Effective rate (as a percent)	3.08%
Maturity Date	May 18, 2051
Future principal payments due on secured and unsecured debt
2021	$ 0
2022	0
2023	0
2024	0
2025	0
Thereafter	850,000
Outstanding Balance	850,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(12,459)
Total Consolidated	$ 837,541
Commercial Paper
Debt Instrument
Stated interest rate (as a percent)	0.23%
Effective rate (as a percent)	0.23%
Future principal payments due on secured and unsecured debt
2022	$ 0
2023	0
2024	0
2025	0
Thereafter	750,000
Commercial Paper
Future principal payments due on secured and unsecured debt
Outstanding Balance	750,000
Unamortized (Deferred Financing Cost), (Discount)/ Premium	(22)
Commercial paper program, gross	750,000
Commercial Paper Program	$ 749,978
London Interbank Offered Rate (LIBOR) | Unsecured senior lines of credit
Debt Instrument
Applicable margin (as a percent)	0.815%