Employee and Retiree Benefit Plans - Components of Net Periodic Benefit Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,706	$ 1,650	$ 5,118	$ 4,950
Interest cost	8,398	8,534	25,182	25,605
Expected return on plan assets	(8,366)	(8,223)	(25,082)	(24,671)
Estimated defined contribution provision	54	53	163	161
Amortization of prior service cost (credit)	579	155	1,737	465
Recognized actuarial loss (gain)	2,363	2,407	7,084	7,222
Total net periodic benefit expense	4,734	4,576	14,202	13,732
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	135	132	405	396
Interest cost	782	874	2,346	2,622
Expected return on plan assets	0	0	0	0
Estimated defined contribution provision	0	0	0	0
Amortization of prior service cost (credit)	(133)	(133)	(399)	(399)
Recognized actuarial loss (gain)	(812)	(767)	(2,436)	(2,315)
Total net periodic benefit expense	$ (28)	$ 106	$ (84)	$ 304