v3.26.1
Retirement and Other Employee Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Pension Plan | Qualified Pension Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost $ 5.6 $ 6.2 $ 11.2 $ 12.5
Expected return on plan assets (9.0) (9.6) (18.0) (19.3)
Amortization of net loss 0.4 0.0 0.8 0.0
Settlement loss     0.0 0.0
Net periodic benefit cost (3.0) (3.4) (6.0) (6.8)
Pension Plan | Unfunded Non-qualified Pension Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost 0.5 0.7 1.0 1.3
Expected return on plan assets 0.0 0.0 0.0 0.0
Amortization of net loss 0.3 0.3 0.6 0.6
Settlement loss     0.0 0.0
Net periodic benefit cost 0.8 1.0 1.6 1.9
Plan Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost 0.0 0.0 0.0 0.0
Expected return on plan assets 0.0 0.0 0.0 0.0
Amortization of net loss 0.0 0.0 0.0 0.0
Settlement loss     0.0 2.5
Net periodic benefit cost $ 0.0 $ 0.0 $ 0.0 $ 2.5