Detail of secured and unsecured debt (Details) - USD ($)
$ in Thousands |
6 Months Ended |
9 Months Ended |
|
Jun. 30, 2025 |
Sep. 30, 2024 |
Feb. 28, 2025 |
| Debt Instrument |
|
|
|
| Effective rate (as a percent) |
4.01%
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
803,624
|
|
|
| 2027 |
350,000
|
|
|
| 2028 |
425,000
|
|
|
| 2029 |
700,000
|
|
|
| Thereafter |
11,100,000
|
|
|
| Principal |
13,378,624
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(84,524)
|
|
|
| Total Consolidated |
$ 13,294,100
|
|
|
| 99 Coolidge Avenue | Alexandria |
|
|
|
| Debt Instrument |
|
|
|
| Noncontrolling Interest, Ownership Percentage by Parent |
76.90%
|
|
|
| Secured notes payable |
|
|
|
| Debt Instrument |
|
|
|
| Effective rate (as a percent) |
7.16%
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| Total Consolidated |
$ 153,500
|
|
|
| Secured notes payable maturing on 11/19/26 |
|
|
|
| Debt Instrument |
|
|
|
| Applicable margin (as a percent) |
2.70%
|
|
|
| Effective rate (as a percent) |
7.16%
|
|
|
| Maturity Date |
Nov. 19, 2026
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
153,624
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
0
|
|
|
| Principal |
153,624
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(124)
|
|
|
| Total Consolidated |
153,500
|
|
|
| Secured notes payable maturing on 11/19/26 | 99 Coolidge Avenue |
|
|
|
| Debt Instrument |
|
|
|
| Debt Instrument, Unused Borrowing Capacity, Amount |
$ 41,700
|
|
|
| Unsecured Debt |
|
|
|
| Debt Instrument |
|
|
|
| Effective rate (as a percent) |
3.97%
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
650,000
|
|
|
| 2027 |
350,000
|
|
|
| 2028 |
425,000
|
|
|
| 2029 |
700,000
|
|
|
| Thereafter |
11,100,000
|
|
|
| Principal |
13,225,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(84,400)
|
|
|
| Total Consolidated |
$ 13,140,600
|
|
|
| Unsecured senior line of credit |
|
|
|
| Debt Instrument |
|
|
|
| Applicable margin (as a percent) |
0.855%
|
0.875%
|
|
| Line of Credit Facility, Maximum Borrowing Capacity |
$ 5,000,000
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| Total Consolidated |
$ 0
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
300,000
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
0
|
|
|
| Principal |
300,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(284)
|
|
|
| Total Consolidated |
$ 299,716
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
350,000
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
0
|
|
|
| Principal |
350,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(408)
|
|
|
| Total Consolidated |
$ 349,592
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
350,000
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
0
|
|
|
| Principal |
350,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(812)
|
|
|
| Total Consolidated |
$ 349,188
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
425,000
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
0
|
|
|
| Principal |
425,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(1,100)
|
|
|
| Total Consolidated |
$ 423,900
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
300,000
|
|
|
| Thereafter |
0
|
|
|
| Principal |
300,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(916)
|
|
|
| Total Consolidated |
$ 299,084
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
400,000
|
|
|
| Thereafter |
0
|
|
|
| Principal |
400,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(1,860)
|
|
|
| Total Consolidated |
$ 398,140
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
450,000
|
|
|
| Principal |
450,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(1,872)
|
|
|
| Total Consolidated |
$ 448,128
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
700,000
|
|
|
| Principal |
700,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(4,339)
|
|
|
| Total Consolidated |
$ 695,661
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
750,000
|
|
|
| Principal |
750,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(4,027)
|
|
|
| Total Consolidated |
$ 745,973
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
900,000
|
|
|
| Principal |
900,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(6,506)
|
|
|
| Total Consolidated |
$ 893,494
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
1,000,000
|
|
|
| Principal |
1,000,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(6,675)
|
|
|
| Total Consolidated |
$ 993,325
|
|
|
| 2.95% Unsecured Senior Notes Payable |
|
|
|
| Debt Instrument |
|
|
|
| Stated interest rate (as a percent) |
2.95%
|
|
|
| Effective rate (as a percent) |
3.07%
|
|
|
| Maturity Date |
Mar. 15, 2034
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
800,000
|
|
|
| Principal |
800,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(6,857)
|
|
|
| Total Consolidated |
$ 793,143
|
|
|
| 4.75% Unsecured Senior Notes Payable |
|
|
|
| Debt Instrument |
|
|
|
| Stated interest rate (as a percent) |
4.75%
|
|
|
| Effective rate (as a percent) |
4.88%
|
|
|
| Maturity Date |
Apr. 15, 2035
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
500,000
|
|
|
| Principal |
500,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(4,730)
|
|
|
| Total Consolidated |
$ 495,270
|
|
|
| 5.50% Unsecured Senior Notes Payable |
|
|
|
| Debt Instrument |
|
|
|
| Stated interest rate (as a percent) |
5.50%
|
|
|
| Effective rate (as a percent) |
5.66%
|
|
|
| Maturity Date |
Oct. 01, 2035
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
550,000
|
|
|
| Principal |
550,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(6,624)
|
|
|
| Total Consolidated |
$ 543,376
|
|
|
| 5.25% Unsecured Senior Notes Payable |
|
|
|
| Debt Instrument |
|
|
|
| Stated interest rate (as a percent) |
5.25%
|
|
5.50%
|
| Effective rate (as a percent) |
5.38%
|
|
|
| Maturity Date |
May 15, 2036
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
400,000
|
|
|
| Principal |
400,000
|
|
$ 550,000
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(3,939)
|
|
|
| Total Consolidated |
$ 396,061
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
300,000
|
|
|
| Principal |
300,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(2,814)
|
|
|
| Total Consolidated |
$ 297,186
|
|
|
| 4.00% Unsecured Senior Notes Payable |
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
700,000
|
|
|
| Principal |
700,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
9,916
|
|
|
| Total Consolidated |
$ 709,916
|
|
|
| 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 |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
850,000
|
|
|
| Principal |
850,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(11,034)
|
|
|
| Total Consolidated |
$ 838,966
|
|
|
| 3.55% Unsecured Senior Notes Payable |
|
|
|
| Debt Instrument |
|
|
|
| Stated interest rate (as a percent) |
3.55%
|
|
|
| Effective rate (as a percent) |
3.63%
|
|
|
| Maturity Date |
Mar. 15, 2052
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
1,000,000
|
|
|
| Principal |
1,000,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(13,450)
|
|
|
| Total Consolidated |
$ 986,550
|
|
|
| 5.15% Unsecured Senior Notes Payable |
|
|
|
| Debt Instrument |
|
|
|
| Stated interest rate (as a percent) |
5.15%
|
|
|
| Effective rate (as a percent) |
5.26%
|
|
|
| Maturity Date |
Apr. 15, 2053
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
500,000
|
|
|
| Principal |
500,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(7,482)
|
|
|
| Total Consolidated |
$ 492,518
|
|
|
| 5.625% Unsecured Senior Notes Payable |
|
|
|
| Debt Instrument |
|
|
|
| Stated interest rate (as a percent) |
5.625%
|
|
|
| Effective rate (as a percent) |
5.71%
|
|
|
| Maturity Date |
May 15, 2054
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
600,000
|
|
|
| Principal |
600,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(6,580)
|
|
|
| Total Consolidated |
593,420
|
|
|
| Commercial Paper |
|
|
|
| Debt Instrument |
|
|
|
| Commercial paper, maximum issuance |
2,500,000
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| Principal |
$ 1,100,000
|
|
|
| Commercial Paper | Unsecured senior line of credit |
|
|
|
| Debt Instrument |
|
|
|
| Effective rate (as a percent) |
4.71%
|
|
|
| Maturity Date |
Jan. 22, 2030
|
|
|
| Future principal payments due on secured and unsecured debt |
|
|
|
| 2025 |
$ 0
|
|
|
| 2026 |
0
|
|
|
| 2027 |
0
|
|
|
| 2028 |
0
|
|
|
| 2029 |
0
|
|
|
| Thereafter |
1,100,000
|
|
|
| Principal |
1,100,000
|
|
|
| Unamortized (Deferred Financing Cost), (Discount)/ Premium |
(2,007)
|
|
|
| Total Consolidated |
$ 1,097,993
|
|
|