Retirement Benefits

6 Months Ended

Jun. 30, 2020

Retirement Benefits [Abstract]

Retirement Benefits

Retirement Benefits

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

	Three Months Ended				Six Months Ended
	June 30, 2020		June 30, 2019		June 30, 2020		June 30, 2019
	(Dollars in thousands)
Service cost	$	3,489	$	3,254	$	6,975	$	6,512
Interest cost	5,710		7,043		11,420		14,092
Expected return on plan assets	(17,993)		(15,112)		(35,987)		(30,225)
Amortization of prior service cost	56		21		111		40
Amortization of actuarial losses	2,934		4,121		5,869		8,240
Net periodic benefit credit	$	(5,804)	$	(673)	$	(11,612)	$	(1,341)

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

	Three Months Ended				Six Months Ended
	June 30, 2020		June 30, 2019		June 30, 2020		June 30, 2019
	(Dollars in thousands)
Service cost	$	25	$	22	$	48	$	44
Interest cost	141		184		283		369
Amortization of prior service credit	(484)		(581)		(967)		(1,163)
Amortization of actuarial gains	(69)		(166)		(139)		(333)
Net periodic benefit credit	$	(387)	$	(541)	$	(775)	$	(1,083)