Retirement Plans and Other Postretirement Benefits - Schedule of Net Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Amortization of:
Portion of benefit charged to expense	$ (10,474)	$ (25,257)	$ (20,339)	$ (49,066)
Pension Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	9,573	13,406	19,730	27,737
Interest cost on benefit obligation	38,418	26,723	76,780	53,746
Expected return on plan assets	(45,908)	(46,494)	(91,469)	(92,888)
Amortization of:
Prior service credit	0	0	0	0
Net actuarial loss (gain)	9,497	3,989	19,210	8,757
Net periodic cost/(benefit)	11,580	(2,376)	24,251	(2,648)
Portion of benefit charged to expense	6,513	(4,722)	13,740	(8,012)
Other Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	2,164	4,017	4,284	8,235
Interest cost on benefit obligation	5,582	4,283	11,255	8,746
Expected return on plan assets	(10,872)	(11,511)	(21,744)	(23,021)
Amortization of:
Prior service credit	(9,447)	(9,447)	(18,894)	(18,894)
Net actuarial loss (gain)	(2,504)	(3,436)	(4,807)	(6,418)
Net periodic cost/(benefit)	(15,077)	(16,094)	(29,906)	(31,352)
Portion of benefit charged to expense	$ (10,948)	$ (11,523)	$ (21,685)	$ (22,418)