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, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,100	$ 6,229	$ 7,994	$ 12,000
Interest cost	8,521	6,520	15,753	13,427
Expected return on plan assets	(10,922)	(10,950)	(21,844)	(21,901)
Amortization of prior service cost	123	75	246	150
Net loss recognition	1,185	939	2,024	2,087
Net periodic benefit cost	2,007	2,813	4,173	5,763
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	532	1,097	1,350	2,160
Interest cost	1,909	1,384	2,953	2,824
Expected return on plan assets	(891)	(700)	(1,782)	(1,400)
Amortization of prior service cost	(263)	(275)	(526)	(550)
Net loss recognition	(8)	870	525	1,760
Net periodic benefit cost	$ 1,279	$ 2,376	$ 2,520	$ 4,794