v3.26.3
Fair value measurements - Assets and Liabilities on Recurring and Nonrecurring Basis (Details)
$ in Thousands
 9 Months Ended
Sep. 30, 2026
USD ($)
transfer
Dec. 31, 2025
USD ($)
Assets and liabilities measured at fair value    
Transfers in Fair Value Hierarchy | transfer 0  
Investments $ 1,735,673 $ 1,501,249
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Unsecured senior notes payable 10,820,687 12,047,394
Currency Swap    
Assets and liabilities measured at fair value    
Derivative Instruments in Hedges, Assets, at Fair Value 3,634  
Derivative Instruments in Hedges, Liabilities, at Fair Value   928
Quoted prices in active markets for identical assets (Level 1) | Currency Swap    
Assets and liabilities measured at fair value    
Derivative Instruments in Hedges, Assets, at Fair Value 0  
Derivative Instruments in Hedges, Liabilities, at Fair Value   0
Significant other observable inputs (Level 2) | Currency Swap    
Assets and liabilities measured at fair value    
Derivative Instruments in Hedges, Assets, at Fair Value 3,634  
Derivative Instruments in Hedges, Liabilities, at Fair Value   928
Significant unobservable input (Level 3) | Currency Swap    
Assets and liabilities measured at fair value    
Derivative Instruments in Hedges, Assets, at Fair Value 0  
Derivative Instruments in Hedges, Liabilities, at Fair Value   0
Book value    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Unsecured senior notes payable 10,820,687 12,047,394
Junior Subordinated Notes, Noncurrent 985,143  
Book value | Commercial Paper    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Commercial Paper 1,091,166 353,161
Book value | Unsecured senior line of credit    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Unsecured senior lines of credit 0 0
Fair Value | Fair value measured on nonrecurring basis    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Real Estate, Held-for-Sale 882,223 581,737
Unsecured senior notes payable, fair value 9,323,013 10,675,433
Junior Subordinated Notes, Fair Value Disclosure 969,100  
Fair Value | Fair value measured on nonrecurring basis | Commercial Paper    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Commercial paper, fair value disclosure 1,091,605 353,189
Fair Value | Fair value measured on nonrecurring basis | Unsecured senior line of credit    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Unsecured senior lines of credit, fair value 0 0
Fair Value | Fair value measured on nonrecurring basis | Quoted prices in active markets for identical assets (Level 1)    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Long-Lived Asset, Held-for-Sale, Fair Value Disclosure 0 0
Unsecured senior notes payable, fair value 0 0
Junior Subordinated Notes, Fair Value Disclosure 0  
Fair Value | Fair value measured on nonrecurring basis | Quoted prices in active markets for identical assets (Level 1) | Commercial Paper    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Commercial paper, fair value disclosure 0 0
Fair Value | Fair value measured on nonrecurring basis | Quoted prices in active markets for identical assets (Level 1) | Unsecured senior line of credit    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Unsecured senior lines of credit, fair value 0 0
Fair Value | Fair value measured on nonrecurring basis | Significant other observable inputs (Level 2)    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Long-Lived Asset, Held-for-Sale, Fair Value Disclosure 0 0
Unsecured senior notes payable, fair value 9,323,013 10,675,433
Junior Subordinated Notes, Fair Value Disclosure 969,100  
Fair Value | Fair value measured on nonrecurring basis | Significant other observable inputs (Level 2) | Commercial Paper    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Commercial paper, fair value disclosure 1,091,605 353,189
Fair Value | Fair value measured on nonrecurring basis | Significant other observable inputs (Level 2) | Unsecured senior line of credit    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Unsecured senior lines of credit, fair value 0 0
Fair Value | Fair value measured on nonrecurring basis | Significant unobservable input (Level 3)    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Long-Lived Asset, Held-for-Sale, Fair Value Disclosure 882,223 581,737
Unsecured senior notes payable, fair value 0 0
Junior Subordinated Notes, Fair Value Disclosure 0  
Fair Value | Fair value measured on nonrecurring basis | Significant unobservable input (Level 3) | Commercial Paper    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Commercial paper, fair value disclosure 0 0
Fair Value | Fair value measured on nonrecurring basis | Significant unobservable input (Level 3) | Unsecured senior line of credit    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Unsecured senior lines of credit, fair value 0 0
Investments In Publicly Traded Companies    
Assets and liabilities measured at fair value    
Investments at fair value 137,577 94,928
Investments In Publicly Traded Companies | Quoted prices in active markets for identical assets (Level 1)    
Assets and liabilities measured at fair value    
Investments at fair value 137,577 94,928
Investments In Publicly Traded Companies | Significant other observable inputs (Level 2)    
Assets and liabilities measured at fair value    
Investments at fair value 0 0
Investments In Publicly Traded Companies | Significant unobservable input (Level 3)    
Assets and liabilities measured at fair value    
Investments at fair value 0 0
Investments in privately held entities that report NAV    
Assets and liabilities measured at fair value    
Investments at fair value 680,443 512,376
Entities without observable price changes | Investments in privately held entities that do not report NAV    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Investments in privately held entities that do not report fair value, book value 406,415 413,324
Entities without observable price changes | Investments in privately held entities that do not report NAV | Fair Value | Fair value measured on nonrecurring basis    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Investments in privately held entities that do not report fair value, book value 79,653 68,738
Entities without observable price changes | Investments in privately held entities that do not report NAV | Fair Value | Fair value measured on nonrecurring basis | Quoted prices in active markets for identical assets (Level 1)    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Investments in privately held entities that do not report fair value, book value 0 0
Entities without observable price changes | Investments in privately held entities that do not report NAV | Fair Value | Fair value measured on nonrecurring basis | Significant other observable inputs (Level 2)    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Investments in privately held entities that do not report fair value, book value 65,424 62,261
Entities without observable price changes | Investments in privately held entities that do not report NAV | Fair Value | Fair value measured on nonrecurring basis | Significant unobservable input (Level 3)    
Fair Value Measurements, Nonrecurring Value Measurement [Abstract]    
Investments in privately held entities that do not report fair value, book value $ 14,229 $ 6,477