Pension Plans and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6,229	$ 6,254	$ 12,000	$ 12,500
Interest cost	6,520	6,530	13,427	13,110
Expected return on plan assets	(10,950)	(9,704)	(21,901)	(19,479)
Amortization of prior service cost	75	75	150	150
Net loss recognition	939	1,688	2,087	3,511
Net periodic benefit cost	2,813	4,843	5,763	9,792
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,097	897	2,160	1,905
Interest cost	1,384	1,309	2,824	2,685
Expected return on plan assets	(700)	(783)	(1,400)	(1,458)
Amortization of prior service cost	(275)	(275)	(550)	(550)
Net loss recognition	870	1,246	1,760	2,419
Net periodic benefit cost	$ 2,376	$ 2,394	$ 4,794	$ 5,001