XML 64 R56.htm IDEA: XBRL DOCUMENT v3.24.3
Employee Benefit Plans: Components of Net Periodic Expense (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2024
Sep. 30, 2023
Sep. 30, 2024
Sep. 30, 2023
Pension Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service Cost $ 0.6 $ 0.6 $ 1.7 $ 1.8
Interest cost 4.1 4.4 12.3 13.1
Expected return on plan assets (4.5) (4.7) (13.4) (14.0)
Net amortization of prior service costs 0.0 0.0 (0.1) 0.0
Recognized net actuarial loss 0.5 0.5 1.5 1.5
Net periodic expense 0.7 0.8 2.0 2.4
Supplemental Employee Retirement Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service Cost 1.3 (0.1) 2.9 1.6
Interest cost 0.4 0.4 1.1 1.1
Expected return on plan assets 0.0 0.0 0.0 0.0
Net amortization of prior service costs 0.0 0.0 0.0 0.0
Recognized net actuarial loss 0.0 0.0 0.0 0.0
Net periodic expense 1.7 0.3 4.0 2.7
Other Postretirement Benefits Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service Cost 0.4 0.4 1.2 1.1
Interest cost 0.6 0.6 1.8 1.8
Expected return on plan assets (0.1) (0.1) (0.2) (0.1)
Net amortization of prior service costs 0.1 0.0 0.1 0.0
Recognized net actuarial loss 0.0 0.0 0.0 0.0
Net periodic expense $ 1.0 $ 0.9 $ 2.9 $ 2.8