Retirement Plans and Other Postretirement Benefits - Schedule of Net Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Amortization of:
Portion of benefit charged to expense	$ (23,809)	$ (27,791)
Pension Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	14,331	15,679
Interest cost on benefit obligation	27,023	24,669
Expected return on plan assets	(46,394)	(50,608)
Amortization of:
Prior service credit	0	0
Net actuarial loss (gain)	4,768	3,985
Net periodic benefit	(272)	(6,275)
Portion of benefit charged to expense	(3,290)	(8,011)
Other Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	4,218	4,557
Interest cost on benefit obligation	4,463	4,162
Expected return on plan assets	(11,510)	(10,361)
Amortization of:
Prior service credit	(9,447)	(9,427)
Net actuarial loss (gain)	(2,982)	(2,405)
Net periodic benefit	(15,258)	(13,474)
Portion of benefit charged to expense	$ (10,895)	$ (9,528)