v3.26.1
Derivative Financial Instruments - Credit Derivatives Sold (Details) - USD ($)
$ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Credit derivatives sold disclosures    
Notional amount $ 1,026.9 $ 946.0
Fair value 19.9 16.1
Maximum future payments $ 1,026.9 $ 946.0
Weighted average expected life 12 years 10 months 24 days 13 years 8 months 12 days
Single name credit default swaps    
Credit derivatives sold disclosures    
Notional amount $ 526.9 $ 446.0
Fair value (4.9) 0.1
Maximum future payments $ 526.9 $ 446.0
Weighted average expected life 5 years 6 months 5 years 3 months 18 days
Single name credit default swaps | Corporate debt securities | AA    
Credit derivatives sold disclosures    
Notional amount $ 117.6 $ 96.7
Fair value 0.6 1.0
Maximum future payments $ 117.6 $ 96.7
Weighted average expected life 6 years 1 month 6 days 6 years 4 months 24 days
Single name credit default swaps | Corporate debt securities | A    
Credit derivatives sold disclosures    
Notional amount $ 157.1 $ 219.3
Fair value (5.7) (3.2)
Maximum future payments $ 157.1 $ 219.3
Weighted average expected life 6 years 4 months 24 days 7 years 2 months 12 days
Single name credit default swaps | Corporate debt securities | BBB    
Credit derivatives sold disclosures    
Notional amount $ 252.2 $ 130.0
Fair value 0.2 2.3
Maximum future payments $ 252.2 $ 130.0
Weighted average expected life 4 years 8 months 12 days 1 year 6 months
Single name total return swaps    
Credit derivatives sold disclosures    
Notional amount $ 500.0 $ 500.0
Fair value 24.8 16.0
Maximum future payments $ 500.0 $ 500.0
Weighted average expected life 20 years 7 months 6 days 21 years 1 month 6 days
Single name total return swaps | Government/municipalities | AAA    
Credit derivatives sold disclosures    
Notional amount $ 40.0 $ 40.0
Fair value 1.6 1.2
Maximum future payments $ 40.0 $ 40.0
Weighted average expected life 29 years 1 month 6 days 29 years 7 months 6 days
Single name total return swaps | Government/municipalities | AA    
Credit derivatives sold disclosures    
Notional amount $ 195.0 $ 195.0
Fair value 6.7 3.5
Maximum future payments $ 195.0 $ 195.0
Weighted average expected life 20 years 20 years 6 months
Single name total return swaps | Government/municipalities | A    
Credit derivatives sold disclosures    
Notional amount $ 210.0 $ 210.0
Fair value 13.7 9.5
Maximum future payments $ 210.0 $ 210.0
Weighted average expected life 21 years 1 month 6 days 21 years 7 months 6 days
Single name total return swaps | Government/municipalities | BBB    
Credit derivatives sold disclosures    
Notional amount $ 55.0 $ 55.0
Fair value 2.8 1.8
Maximum future payments $ 55.0 $ 55.0
Weighted average expected life 14 years 9 months 18 days 15 years 3 months 18 days