Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Plans
Components of net periodic benefit cost:
Service cost	$ 2,632	$ 3,491	$ 3,953
Interest cost	15,237	9,248	7,512
Expected return on plan assets	(16,512)	(16,023)	(16,337)
Amortization of prior service cost	176	174	110
Settlement loss (gain)	(101)	1,189	(18)
Other adjustments	0	0	(191)
Net loss (gain) recognition	(938)	734	3,764
Net periodic benefit cost (income)	494	(1,187)	(1,207)
Other Plans
Components of net periodic benefit cost:
Service cost	11	24	33
Interest cost	1,012	761	727
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Settlement loss (gain)	0	0	0
Other adjustments	0	0	0
Net loss (gain) recognition	(737)	(73)	(43)
Net periodic benefit cost (income)	$ 286	$ 712	$ 717