v3.25.2
Allowance for Credit Losses (Changes in The Allowance for Credit Losses Related to Debt Securities Held to Maturity) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
HELD TO MATURITY DEBT SECURITIES        
Balance at Beginning of Period $ 6.7 $ 12.4 $ 6.5 $ 12.7
Provision for Credit Losses 0.2 (1.5) 0.4 (1.8)
Balance at End of Period 6.9 10.9 6.9 10.9
CORPORATE DEBT        
HELD TO MATURITY DEBT SECURITIES        
Balance at Beginning of Period 0.3 0.8 0.3 0.9
Provision for Credit Losses 0.0 (0.3) 0.0 (0.4)
Balance at End of Period 0.3 0.5 0.3 0.5
NON-U.S. GOVERNMENT        
HELD TO MATURITY DEBT SECURITIES        
Balance at Beginning of Period 2.1 3.5 2.0 3.5
Provision for Credit Losses 0.1 (0.9) 0.2 (0.9)
Balance at End of Period 2.2 2.6 2.2 2.6
SUB-SOVEREIGN, SUPRANATIONAL, AND NON-U.S. AGENCY BONDS        
HELD TO MATURITY DEBT SECURITIES        
Balance at Beginning of Period 1.1 2.1 1.1 2.2
Provision for Credit Losses 0.1 (0.4) 0.1 (0.5)
Balance at End of Period 1.2 1.7 1.2 1.7
OBLIGATIONS OF STATES AND POICITAL SUBDIVISIONS        
HELD TO MATURITY DEBT SECURITIES        
Balance at Beginning of Period 0.9 1.1 0.9 1.2
Provision for Credit Losses 0.0 (0.1) 0.0 (0.2)
Balance at End of Period 0.9 1.0 0.9 1.0
COVERED BONDS        
HELD TO MATURITY DEBT SECURITIES        
Balance at Beginning of Period 0.0 0.1 0.0 0.1
Provision for Credit Losses 0.0 0.0 0.0 0.0
Balance at End of Period 0.0 0.1 0.0 0.1
OTHER        
HELD TO MATURITY DEBT SECURITIES        
Balance at Beginning of Period 2.3 4.8 2.2 4.8
Provision for Credit Losses 0.0 0.2 0.1 0.2
Balance at End of Period $ 2.3 $ 5.0 $ 2.3 $ 5.0