Consolidated and unconsolidated real estate joint ventures - Unconsolidated real estate joint ventures (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2023	Dec. 31, 2022
Schedule of Equity Method Investments
Investments in unconsolidated real estate joint ventures	$ 37,695	$ 38,435
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 6,700
Unconsolidated Real Estate Joint Ventures Debt
Interest Rate	3.70%
Debt Balance at 100%	$ 11,202,835
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Unconsolidated Real Estate Joint Ventures Debt
Debt instrument, borrowing capacity	668,250
Debt Balance at 100%	$ 649,401
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Unconsolidated Real Estate Joint Ventures Debt
Fixed SOFR floor rate	0.75%
1655 and 1725 Third Street
Schedule of Equity Method Investments
Investments in unconsolidated real estate joint ventures	$ 11,929	12,996
Equity Method Investment, Ownership Percentage	10.00%
1450 Research Boulevard
Schedule of Equity Method Investments
Investments in unconsolidated real estate joint ventures	$ 5,935	5,625
Equity Method Investment, Ownership Percentage	73.20%
101 West Dickman Street
Schedule of Equity Method Investments
Investments in unconsolidated real estate joint ventures	$ 9,006	8,678
Equity Method Investment, Ownership Percentage	57.90%
Other unconsolidated real estate joint ventures
Schedule of Equity Method Investments
Investments in unconsolidated real estate joint ventures	$ 10,825	$ 11,136
1401/1413 Research Boulevard
Schedule of Equity Method Investments
Equity Method Investment, Ownership Percentage	65.00%
Secured debt maturing on 12/23/24 \| 1401/1413 Research Boulevard
Unconsolidated Real Estate Joint Ventures Debt
Maturity Date	Dec. 23, 2024
Stated interest rate (as a percent)	2.70%
Interest Rate	3.31%
Debt instrument, borrowing capacity	$ 28,500
Debt Balance at 100%	$ 28,288
Secured debt maturing on 3/10/25 \| 1655 and 1725 Third Street
Unconsolidated Real Estate Joint Ventures Debt
Maturity Date	Mar. 10, 2025
Stated interest rate (as a percent)	4.50%
Interest Rate	4.57%
Debt instrument, borrowing capacity	$ 600,000
Debt Balance at 100%	$ 599,399
Secured debt maturing on 11/10/26 \| 101 West Dickman Street
Unconsolidated Real Estate Joint Ventures Debt
Maturity Date	Nov. 10, 2026
Interest Rate	7.37%
Debt instrument, borrowing capacity	$ 26,750
Debt Balance at 100%	$ 13,949
Secured debt maturing on 11/10/26 \| 101 West Dickman Street \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Unconsolidated Real Estate Joint Ventures Debt
Stated interest rate (as a percent)	1.95%
Secured debt maturing on 12/10/26 \| 1450 Research Boulevard
Unconsolidated Real Estate Joint Ventures Debt
Maturity Date	Dec. 10, 2026
Interest Rate	7.43%
Debt instrument, borrowing capacity	$ 13,000
Debt Balance at 100%	$ 7,765
Secured debt maturing on 12/10/26 \| 1450 Research Boulevard \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Unconsolidated Real Estate Joint Ventures Debt
Stated interest rate (as a percent)	1.95%

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