Retirement Benefits

9 Months Ended

Sep. 30, 2021

Retirement Benefits [Abstract]

Retirement Benefits

Retirement Benefits

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

	Three Months Ended				Nine Months Ended
	Sept. 30, 2021		Sept. 30, 2020		Sept. 30, 2021		Sept. 30, 2020
	(Dollars in thousands)
Service cost	$	3,177	$	2,983	$	10,754	$	9,958
Interest cost	4,579		5,816		13,288		17,236
Expected return on plan assets	(19,892)		(18,104)		(59,590)		(54,091)
Amortization of prior service cost	67		43		183		154
Amortization of actuarial losses	3,464		2,993		9,518		8,862
Net periodic benefit credit	$	(8,605)	$	(6,269)	$	(25,847)	$	(17,881)

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

	Three Months Ended				Nine Months Ended
	Sept. 30, 2021		Sept. 30, 2020		Sept. 30, 2021		Sept. 30, 2020
	(Dollars in thousands)
Service cost	$	25	$	18	$	81	$	66
Interest cost	82		142		272		425
Amortization of prior service credit	(460)		(487)		(1,373)		(1,454)
Amortization of actuarial gains	(137)		(115)		(232)		(254)
Net periodic benefit credit	$	(490)	$	(442)	$	(1,252)	$	(1,217)