Retirement Benefits

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Retirement Benefits

Retirement Benefits

The components of the net periodic pension benefit credit for the three months ended March 31 were as follows:

	2021		2020
	(Dollars in thousands)
Service cost	$	3,788	$	3,486
Interest cost	4,354		5,710
Expected return on plan assets	(19,848)		(17,993)
Amortization of prior service cost	58		55
Amortization of actuarial losses	3,026		2,934
Net periodic benefit credit	$	(8,622)	$	(5,808)

The components of the net periodic other postretirement benefit credit for the three months ended March 31 were as follows:

	2021		2020
	(Dollars in thousands)
Service cost	$	28	$	23
Interest cost	95		142
Amortization of prior service credit	(456)		(483)
Amortization of actuarial gains	(48)		(70)
Net periodic benefit credit	$	(381)	$	(388)