XML 73 R52.htm IDEA: XBRL DOCUMENT v3.24.3
INVESTMENTS - Schedule of Gross Unrealized Losses and Fair Values for Investments in Unrealized Loss Position (Details) - USD ($)
$ in Millions
Sep. 30, 2024
Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months $ 3.6 $ 35.2
Gross unrealized losses, less than 12 months (0.1) (1.9)
Fair value, 12 months or greater 295.0 843.7
Gross unrealized losses, 12 months or greater (6.8) (25.6)
Fair value, total 298.6 878.9
Gross unrealized losses, total (6.9) (27.5)
U.S. government and agency securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 0.0 0.0
Gross unrealized losses, less than 12 months 0.0 0.0
Fair value, 12 months or greater 34.0 67.1
Gross unrealized losses, 12 months or greater (1.2) (2.8)
Fair value, total 34.0 67.1
Gross unrealized losses, total (1.2) (2.8)
Asset-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 3.6 10.2
Gross unrealized losses, less than 12 months (0.1) (1.8)
Fair value, 12 months or greater 65.3 172.7
Gross unrealized losses, 12 months or greater (1.5) (6.0)
Fair value, total 68.9 182.9
Gross unrealized losses, total (1.6) (7.8)
Corporate debt securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 0.0 25.0
Gross unrealized losses, less than 12 months 0.0 (0.1)
Fair value, 12 months or greater 193.0 601.3
Gross unrealized losses, 12 months or greater (4.0) (16.6)
Fair value, total 193.0 626.3
Gross unrealized losses, total (4.0) (16.7)
Municipal securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 0.0 0.0
Gross unrealized losses, less than 12 months 0.0 0.0
Fair value, 12 months or greater 2.7 2.6
Gross unrealized losses, 12 months or greater (0.1) (0.2)
Fair value, total 2.7 2.6
Gross unrealized losses, total $ (0.1) $ (0.2)