Income Taxes - Schedule of Analysis of Deferred Tax Assets and Deferred Tax Liabilities Showing Tax Effects of Significant Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets
Property and leasehold costs	$ 235,509	$ 225,379
Liabilities for dismantlements	40,242	36,719
Postretirement and other employee benefits	66,418	66,293
U. S. net operating loss	224,956	289,594
Investment in partnership	20,307	9,096
Other deferred tax assets	97,660	100,352
Total gross deferred tax assets	685,092	727,433
Less: Valuation allowance	(157,807)	(149,498)
Net deferred tax assets	527,285	577,935
Deferred tax liabilities
Deferred tax on undistributed foreign earnings	(5,000)	(5,000)
Accumulated depreciation, depletion and amortization	(812,727)	(811,178)
Other deferred tax liabilities	(87,895)	(97,547)
Total gross deferred tax liabilities	(905,622)	(913,725)
Net deferred tax (liabilities) assets	$ (378,337)	$ (335,790)