Pension Plans and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5,771	$ 6,246
Interest cost	6,907	6,580
Expected return on plan assets	(10,951)	(9,775)
Amortization of prior service cost	75	75
Net loss recognition	1,148	1,823
Net periodic benefit cost	2,950	4,949
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,063	1,008
Interest cost	1,440	1,376
Expected return on plan assets	(700)	(675)
Amortization of prior service cost	(275)	(275)
Net loss recognition	890	1,173
Net periodic benefit cost	$ 2,418	$ 2,607