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Fair Value Measurements (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 974.2  
Debt Securities, Available-for-sale 974.4  
Fair Value, Recurring    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale 974.4 $ 939.6
Fair Value, Recurring | Corporate Debt Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale 481.5 451.9
Fair Value, Recurring | Municipal obligations [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale 13.5 14.9
Fair Value, Recurring | US Government Sponsored Agencies [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale 77.6 79.6
Fair Value, Recurring | Foreign Government Obligations [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale 11.7 11.7
Fair Value, Recurring | Asset-backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale 390.1 381.5
Fair Value, Recurring | Location, Statement of Financial Position, Balance [Axis]: us-gaap:ShortTermInvestments    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 974.2 931.6
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 4.0 8.8
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (3.8) (0.8)
Debt Securities, Available-for-sale 974.4 939.6
Fair Value, Recurring | Location, Statement of Financial Position, Balance [Axis]: us-gaap:ShortTermInvestments | Corporate Debt Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 481.5 447.4
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 2.1 4.6
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (2.1) (0.1)
Debt Securities, Available-for-sale 481.5 451.9
Fair Value, Recurring | Location, Statement of Financial Position, Balance [Axis]: us-gaap:ShortTermInvestments | Municipal obligations [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 13.3 14.6
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 0.2 0.3
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax 0.0 0.0
Debt Securities, Available-for-sale 13.5 14.9
Fair Value, Recurring | Location, Statement of Financial Position, Balance [Axis]: us-gaap:ShortTermInvestments | US Government Sponsored Agencies [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 77.9 79.1
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 0.1 0.5
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (0.4) 0.0
Debt Securities, Available-for-sale 77.6 79.6
Fair Value, Recurring | Location, Statement of Financial Position, Balance [Axis]: us-gaap:ShortTermInvestments | Foreign Government Obligations [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 11.7 11.6
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 0.0 0.1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax 0.0 0.0
Debt Securities, Available-for-sale 11.7 11.7
Fair Value, Recurring | Location, Statement of Financial Position, Balance [Axis]: us-gaap:ShortTermInvestments | Asset-backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 389.8 378.9
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 1.6 3.3
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (1.3) (0.7)
Debt Securities, Available-for-sale $ 390.1 $ 381.5