v3.25.2
Assets and Liabilities Measured at Fair Value on a Recurring Basis - Schedule of fair value assets and liabilities measured on recurring basis (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Real estate properties $ 15,451.0 $ 15,607.0
Real estate operating business 1,033.1 931.8
Marketable securities:    
Marketable securities excluding real estate-related 1,155.9 1,211.8
Loans payable (933.3) (1,585.5)
Line of credit (219.0) 0.0
Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Real estate properties 15,451.0 15,607.0
Real estate joint ventures 5,220.8 5,381.4
Real estate operating business 1,033.1 931.8
Marketable securities:    
Loans receivable 849.1 877.8
Loans payable (933.3) (1,585.5)
Line of credit (219.0)  
Fair Value, Measurements, Recurring | Term Loan    
Marketable securities:    
Other unsecured debt (891.3) (877.0)
Fair Value, Measurements, Recurring | U.S. government agency notes    
Marketable securities:    
Marketable securities excluding real estate-related 741.4 701.4
Fair Value, Measurements, Recurring | Reverse repurchase agreements    
Marketable securities:    
Marketable securities excluding real estate-related 312.3  
Fair Value, Measurements, Recurring | U.S. treasury securities    
Marketable securities:    
Marketable securities excluding real estate-related 102.2 510.4
Fair Value, Measurements, Recurring | Level 1: Quoted Prices in Active Markets for Identical Assets    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Real estate properties 0.0 0.0
Real estate joint ventures 0.0 0.0
Real estate operating business 0.0 0.0
Marketable securities:    
Loans receivable 0.0 0.0
Loans payable 0.0 0.0
Line of credit 0.0  
Fair Value, Measurements, Recurring | Level 1: Quoted Prices in Active Markets for Identical Assets | Term Loan    
Marketable securities:    
Other unsecured debt 0.0 0.0
Fair Value, Measurements, Recurring | Level 1: Quoted Prices in Active Markets for Identical Assets | U.S. government agency notes    
Marketable securities:    
Marketable securities excluding real estate-related 0.0 0.0
Fair Value, Measurements, Recurring | Level 1: Quoted Prices in Active Markets for Identical Assets | Reverse repurchase agreements    
Marketable securities:    
Marketable securities excluding real estate-related 0.0  
Fair Value, Measurements, Recurring | Level 1: Quoted Prices in Active Markets for Identical Assets | U.S. treasury securities    
Marketable securities:    
Marketable securities excluding real estate-related 0.0 0.0
Fair Value, Measurements, Recurring | Level 2: Significant Other Observable Inputs    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Real estate properties 0.0 0.0
Real estate joint ventures 0.0 0.0
Real estate operating business 0.0 0.0
Marketable securities:    
Loans receivable 0.0 0.0
Loans payable 0.0 0.0
Line of credit 0.0  
Fair Value, Measurements, Recurring | Level 2: Significant Other Observable Inputs | Term Loan    
Marketable securities:    
Other unsecured debt (891.3) (877.0)
Fair Value, Measurements, Recurring | Level 2: Significant Other Observable Inputs | U.S. government agency notes    
Marketable securities:    
Marketable securities excluding real estate-related 741.4 701.4
Fair Value, Measurements, Recurring | Level 2: Significant Other Observable Inputs | Reverse repurchase agreements    
Marketable securities:    
Marketable securities excluding real estate-related 312.3  
Fair Value, Measurements, Recurring | Level 2: Significant Other Observable Inputs | U.S. treasury securities    
Marketable securities:    
Marketable securities excluding real estate-related 102.2 510.4
Fair Value, Measurements, Recurring | Level 3: Significant Unobservable Inputs    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Real estate properties 15,451.0 15,607.0
Real estate joint ventures 5,220.8 5,381.4
Real estate operating business 1,033.1 931.8
Marketable securities:    
Loans receivable 849.1 877.8
Loans payable (933.3) (1,585.5)
Line of credit (219.0)  
Fair Value, Measurements, Recurring | Level 3: Significant Unobservable Inputs | Term Loan    
Marketable securities:    
Other unsecured debt 0.0 0.0
Fair Value, Measurements, Recurring | Level 3: Significant Unobservable Inputs | U.S. government agency notes    
Marketable securities:    
Marketable securities excluding real estate-related 0.0 0.0
Fair Value, Measurements, Recurring | Level 3: Significant Unobservable Inputs | Reverse repurchase agreements    
Marketable securities:    
Marketable securities excluding real estate-related 0.0  
Fair Value, Measurements, Recurring | Level 3: Significant Unobservable Inputs | U.S. treasury securities    
Marketable securities:    
Marketable securities excluding real estate-related $ 0.0 $ 0.0