Employee Benefit Plans and Other Postretirement Benefits - Schedule of Obligation and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in plan assets:
Pension and postretirement assets	$ 413,107	$ 320,133
Pension and SERPA Benefits
Change in benefit obligation:
Benefit obligation, beginning of period	1,553,912	2,174,595
Service cost	5,174	19,052	$ 24,570
Interest cost	81,911	61,890	61,988
Actuarial loss / (gains)	35,608	(561,142)
Plan participant contributions	0	0
Plan amendments	0	0
Benefits paid	(106,493)	(137,645)
Settlements	(1,835)	(2,838)
Benefit obligation, end of period	1,568,277	1,553,912	2,174,595
Change in plan assets:
Fair value of plan assets, beginning of period	1,809,543	2,486,467
Return on plan assets	198,212	(539,800)
Plan participant contributions	0	0
Benefits paid	(105,931)	(137,124)
Fair value of plan assets, end of period	1,901,824	1,809,543	2,486,467
Funded status of the plan	333,547	255,631
Pension and postretirement assets	343,619	268,317
Accrued liabilities	(1,129)	(1,331)
Pension and postretirement liabilities	(8,943)	(11,355)
Total benefits included in balance sheet	333,547	255,631
Prior service credits	2,886	3,461
Actuarial losses (gains)	277,825	289,340
Amounts included in other comprehensive income, net of tax	280,711	292,801
Postretirement Healthcare Benefits
Change in benefit obligation:
Benefit obligation, beginning of period	210,811	286,301
Service cost	3,184	4,642	5,147
Interest cost	11,089	7,617	6,505
Actuarial loss / (gains)	(18,350)	(67,903)
Plan participant contributions	1,790	2,029
Plan amendments	12,959	0
Benefits paid	(14,977)	(16,657)
Settlements	0	(5,218)
Benefit obligation, end of period	206,506	210,811	286,301
Change in plan assets:
Fair value of plan assets, beginning of period	205,803	262,945
Return on plan assets	29,211	(48,257)
Plan participant contributions	1,790	2,029
Benefits paid	(11,637)	(10,914)
Fair value of plan assets, end of period	225,167	205,803	$ 262,945
Funded status of the plan	18,661	(5,008)
Pension and postretirement assets	69,489	51,816
Accrued liabilities	0	(224)
Pension and postretirement liabilities	(50,828)	(56,600)
Total benefits included in balance sheet	18,661	(5,008)
Prior service credits	8,542	(1,884)
Actuarial losses (gains)	(59,631)	(39,699)
Amounts included in other comprehensive income, net of tax	$ (51,089)	$ (41,583)