Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2023

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Credit)

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

	2023		2022
	(Dollars in thousands)
Service cost	$	2,229	$	3,300
Interest cost	8,709		5,159
Expected return on plan assets	(10,189)		(17,314)
Amortization of prior service cost	28		55
Amortization of actuarial losses	2,945		1,155
Net periodic benefit cost (credit)	$	3,722	$	(7,645)

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

	2023		2022
	(Dollars in thousands)
Service cost	$	14	$	25
Interest cost	189		109
Amortization of prior service credit	(235)		(416)
Amortization of actuarial gains	(161)		(77)
Net periodic benefit credit	$	(193)	$	(359)