Employee and Retiree Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2023

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Expense

The table that follows provides the components of net periodic benefit expense for the three-month periods ended March 31, 2023 and 2022.

	Three Months Ended March 31,
	Pension Benefits				Other Postretirement Benefits
(Thousands of dollars)	2023		2022		2023		2022
Service cost	$	1,650	$	2,129	$	132	$	292
Interest cost	8,507		5,243		874		574
Expected return on plan assets	(8,194)		(8,138)		–		–
Amortization of prior service cost (credit)	155		600		(133)		(133)
Recognized actuarial loss (gain)	2,401		3,822		(781)		(77)
Net periodic benefit expense	$	4,519	$	3,656	$	92	$	656