Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2022

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

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

	2022		2021
	(Dollars in thousands)
Service cost	$	3,300	$	3,788
Interest cost	5,159		4,354
Expected return on plan assets	(17,314)		(19,848)
Amortization of prior service cost	55		58
Amortization of actuarial losses	1,155		3,026
Net periodic benefit credit	$	(7,645)	$	(8,622)

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

	2022		2021
	(Dollars in thousands)
Service cost	$	25	$	28
Interest cost	109		95
Amortization of prior service credit	(416)		(456)
Amortization of actuarial gains	(77)		(48)
Net periodic benefit credit	$	(359)	$	(381)