Retirement Benefits

9 Months Ended

Sep. 30, 2024

Retirement Benefits [Abstract]

Retirement Benefits

Retirement Benefits

The components of the net periodic pension benefit cost were as follows:

	Three Months Ended				Nine Months Ended
	Sept. 30, 2024		Sept. 30, 2023		Sept. 30, 2024		Sept. 30, 2023
	(Dollars in thousands)
Service cost	$	1,990	$	1,962	$	6,319	$	6,425
Interest cost	8,592		8,617		25,413		26,050
Expected return on plan assets	(10,772)		(10,211)		(32,314)		(30,587)
Amortization of prior service cost	22		29		68		82
Amortization of actuarial losses	2,232		2,845		5,937		8,729
Net periodic benefit cost	$	2,064	$	3,242	$	5,423	$	10,699

The components of the net periodic other postretirement benefit cost (credit) were as follows:

	Three Months Ended				Nine Months Ended
	Sept. 30, 2024		Sept. 30, 2023		Sept. 30, 2024		Sept. 30, 2023
	(Dollars in thousands)
Service cost	$	8	$	12	$	22	$	38
Interest cost	151		181		483		559
Amortization of prior service credit	(5)		(237)		(15)		(705)
Amortization of actuarial gains	(102)		(141)		(270)		(464)
Net periodic benefit cost (credit)	$	52	$	(185)	$	220	$	(572)