Employee and Retiree Benefit Plans - Components of Net Periodic Benefit Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,650	$ 2,129	$ 4,950	$ 6,387
Interest cost	8,534	5,163	25,605	15,545
Expected return on plan assets	(8,223)	(7,999)	(24,671)	(24,091)
Estimated defined contribution provision	53	0	161	0
Amortization of prior service cost (credit)	155	582	465	1,761
Recognized actuarial loss (gain)	2,407	3,822	7,222	11,466
Total net periodic benefit expense	4,576	3,697	13,732	11,068
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	132	292	396	876
Interest cost	874	574	2,622	1,722
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)	(767)	(77)	(2,315)	(232)
Total net periodic benefit expense	$ 106	$ 656	$ 304	$ 1,967