v3.26.1
Investments, Continuous Loss Position (Details)
$ in Millions
Jun. 30, 2026
USD ($)
shares
shares
Dec. 31, 2025
USD ($)
shares
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 907.3 $ 423.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 251.0 278.2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (12.0) (2.1)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss $ (16.4) $ (14.6)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 798 461
Debt Securities, number of issues in loss position, 12 months or greater 262 282
Debt Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 907.3 $ 423.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 251.0 278.2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (12.0) (2.1)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss $ (16.4) $ (14.6)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 798 461
Debt Securities, number of issues in loss position, 12 months or greater | shares 262 282
US Treasury Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 41.9 $ 0.0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 9.8 13.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (0.6) 0.0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss $ (0.6) $ (0.9)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 9 0
Debt Securities, number of issues in loss position, 12 months or greater 2 2
US States and Political Subdivisions Debt Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 24.0 $ 21.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 11.2 14.0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (0.2) (0.2)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss $ (0.5) $ (0.6)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 13 6
Debt Securities, number of issues in loss position, 12 months or greater 6 7
Corporate Debt Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 241.1 $ 96.9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 168.0 175.3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (4.1) (0.7)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss $ (12.9) $ (11.5)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 87 32
Debt Securities, number of issues in loss position, 12 months or greater 85 91
Residential Mortgage Backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 423.1 $ 252.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 55.1 68.2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (5.0) (0.9)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss $ (2.3) $ (1.5)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 129 53
Debt Securities, number of issues in loss position, 12 months or greater 30 39
Commercial Mortgage Backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 9.3 $ 0.0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss $ (0.1) $ 0.0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 7 0
Asset-backed Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 81.8 $ 32.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss $ (0.7) $ (0.1)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 48 15
Other Debt Obligations [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 86.1 $ 19.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 6.9 7.3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (1.3) (0.2)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss $ (0.1) $ (0.1)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]    
Debt Securities, number of issues in loss position, less than 12 months | shares 505 355
Debt Securities, number of issues in loss position, 12 months or greater | shares 139 143