Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Consolidated Statements of Comprehensive Income
Net Income (Loss)	$ 464,038	$ 1,330,914	$ 337,573
Derivative instruments
Comprehensive income before tax		1,763	2,128
Other comprehensive income, derivative instruments, net of tax		1,763	2,128
Pension, postretirement and other post-employment benefits
Comprehensive (loss) income before tax	(24,364)	57,930	47,562
Provision for (benefit from) income taxes	1,662	(12,548)
Other comprehensive loss, pension, postretirement and other post-employment benefits, net of tax	(22,702)	45,382	47,562
Available-for-sale securities
Comprehensive income before tax	39	161	169
Provision for (benefit from) income taxes	16	(35)
Other comprehensive (loss) income, available-for-sale securities, net of tax	55	126	169
Total other comprehensive (loss) income	(22,647)	47,271	49,859
Total comprehensive income	$ 441,391	$ 1,378,185	$ 387,432