v3.26.3
Retirement Benefits
 9 Months Ended
Sep. 30, 2026
Retirement Benefits [Abstract]  
Retirement Benefits Retirement Benefits
The components of the net periodic pension benefit cost were as follows:
Three Months EndedNine Months Ended
Sept. 30, 2026Sept. 30, 2025Sept. 30, 2026Sept. 30, 2025
(Dollars in thousands)
Service cost$1,486 $1,686 $4,619 $5,598 
Interest cost7,640 8,104 22,935 24,400 
Expected return on plan assets(10,336)(10,273)(31,155)(30,786)
Amortization of prior service (credit) cost (14)46 (42)59 
Amortization of actuarial losses1,870 1,726 5,437 5,502 
Net periodic benefit cost $646 $1,289 $1,794 $4,773 
 
The components of the net periodic other postretirement benefit (credit) were as follows:
Three Months EndedNine Months Ended
Sept. 30, 2026Sept. 30, 2025Sept. 30, 2026Sept. 30, 2025
(Dollars in thousands)
Service cost$— $— $5 $10 
Interest cost86 20 269 322 
Amortization of prior service credit(20)(16)(53)(45)
Amortization of actuarial gains(222)(414)(536)(586)
Net periodic benefit (credit) $(156)$(410)$(315)$(299)