v3.26.1
INVESTMENTS - Schedule of Gross Realized Gains and Losses (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Gain (Loss) on Securities [Line Items]    
Less than 12 months, fair value $ 112.1 $ 33.5
Less than 12 months, unrealized losses (1.2) (0.1)
12 months or longer, fair value 36.0 20.2
12 months or longer, unrealized losses (0.5) (0.2)
Total fair value 148.1 53.7
Total unrealized losses (1.7) (0.3)
Short-term investments    
Gain (Loss) on Securities [Line Items]    
Less than 12 months, fair value 0.0 0.0
Less than 12 months, unrealized losses 0.0 0.0
12 months or longer, fair value 0.8 0.5
12 months or longer, unrealized losses 0.0 0.0
Total fair value 0.8 0.5
Total unrealized losses 0.0 0.0
U.S. Treasuries    
Gain (Loss) on Securities [Line Items]    
Less than 12 months, fair value 2.0 0.0
Less than 12 months, unrealized losses 0.0 0.0
12 months or longer, fair value 0.0 0.8
12 months or longer, unrealized losses 0.0 0.0
Total fair value 2.0 0.8
Total unrealized losses 0.0 0.0
Municipal    
Gain (Loss) on Securities [Line Items]    
Less than 12 months, fair value 0.1  
Less than 12 months, unrealized losses 0.0  
12 months or longer, fair value 0.0  
12 months or longer, unrealized losses 0.0  
Total fair value 0.1  
Total unrealized losses 0.0  
Corporate    
Gain (Loss) on Securities [Line Items]    
Less than 12 months, fair value 40.2 4.8
Less than 12 months, unrealized losses (0.5) 0.0
12 months or longer, fair value 2.1 0.0
12 months or longer, unrealized losses 0.0 0.0
Total fair value 42.2 4.8
Total unrealized losses (0.5) 0.0
Mortgage and other asset-backed securities    
Gain (Loss) on Securities [Line Items]    
Less than 12 months, fair value 69.8 28.8
Less than 12 months, unrealized losses (0.7) (0.1)
12 months or longer, fair value 33.1 18.8
12 months or longer, unrealized losses (0.5) (0.2)
Total fair value 102.9 47.6
Total unrealized losses $ (1.2) $ (0.3)