Retirement Plans and Other Postretirement Benefits - Schedule of Net Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Amortization of:
Portion of benefit charged to expense	$ (25,257)	$ (28,175)	$ (49,066)	$ (55,966)
Pension Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	13,406	14,939	27,737	30,618
Interest cost on benefit obligation	26,723	24,614	53,746	49,283
Expected return on plan assets	(46,494)	(50,706)	(92,888)	(101,314)
Amortization of:
Prior service credit	0	0	0	0
Net actuarial loss (gain)	3,989	3,989	8,757	7,974
Net periodic benefit	(2,376)	(7,164)	(2,648)	(13,439)
Portion of benefit charged to expense	(4,722)	(8,614)	(8,012)	(16,625)
Other Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	4,017	4,341	8,235	8,898
Interest cost on benefit obligation	4,283	4,095	8,746	8,257
Expected return on plan assets	(11,511)	(10,361)	(23,021)	(20,722)
Amortization of:
Prior service credit	(9,447)	(9,427)	(18,894)	(18,854)
Net actuarial loss (gain)	(3,436)	(2,641)	(6,418)	(5,046)
Net periodic benefit	(16,094)	(13,993)	(31,352)	(27,467)
Portion of benefit charged to expense	$ (11,523)	$ (9,608)	$ (22,418)	$ (19,136)