Pension plans and other postretirement benefits (Tables)

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Net Periodic Defined Benefit Cost for Defined Benefit Plans

The Company provides defined benefit pension and other postretirement benefits (including health care and life insurance benefits) to qualified retired employees. Net periodic cost (benefit) for defined benefit plans consisted of the following:

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended September 30
	2023			2022			2023			2022
	(In thousands)
Service cost	$	2,837		$	4,423		$	400		$	689
Interest cost on projected benefit obligation		28,862			22,060			703			581
Expected return on plan assets		(50,315	)		(50,188	)		—			—
Amortization of prior service cost (credit)		52			129			(515	)		(693	)
Amortization of net actuarial loss (gain)		(537	)		4,974			(692	)		(370	)
Net periodic cost (benefit)	$	(19,101	)	$	(18,602	)	$	(104	)	$	207

	Pension Benefits						Other Postretirement Benefits
	Nine Months Ended September 30
	2023			2022			2023			2022
	(In thousands)
Service cost	$	8,512		$	13,237		$	1,200		$	1,914
Interest cost on projected benefit obligation		86,585			60,407			2,109			1,607
Expected return on plan assets		(150,945	)		(137,421	)		—			—
Amortization of prior service cost (credit)		155			387			(1,545	)		(2,079	)
Amortization of net actuarial loss (gain)		(1,610	)		14,921			(2,076	)		(1,111	)
Net periodic cost (benefit)	$	(57,303	)	$	(48,469	)	$	(312	)	$	331