v3.25.2
FAIR VALUE MEASUREMENTS - Fair Value of Other Temporary Investments and Cash (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value $ 4,609.7 $ 4,395.1
Total Other Temporary Investments and Restricted Cash    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost 241.2 236.9
Gross Unrealized Gains 25.1 26.9
Gross Unrealized Losses (3.0) (5.3)
Fair Value 263.3 258.5
Restricted Cash    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost 51.3 43.1
Gross Unrealized Gains 0.0 0.0
Gross Unrealized Losses 0.0 0.0
Fair Value 51.3 43.1
Other Cash Deposits    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost 16.1 13.9
Gross Unrealized Gains 0.0 0.0
Gross Unrealized Losses 0.0 0.0
Fair Value 16.1 13.9
Fixed Income Securities – Mutual Funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost 159.8 167.2
Gross Unrealized Gains 0.0 0.0
Gross Unrealized Losses (3.0) (5.3)
Fair Value 156.8 161.9
Equity Securities – Mutual Funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cost 14.0 12.7
Gross Unrealized Gains 25.1 26.9
Gross Unrealized Losses 0.0 0.0
Fair Value $ 39.1 $ 39.6