Income Taxes - Analysis of Deferred Tax Assets and Deferred Tax Liabilities Showing Tax Effects of Significant Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets
Property and leasehold costs	$ 240,065	$ 242,467
Liabilities for dismantlements	34,258	31,017
Postretirement and other employee benefits	82,437	86,798
U. S. net operating loss	357,490	442,699
Investment in partnership	14,655	11,595
Other deferred tax assets	48,778	111,212
Total gross deferred tax assets	777,683	925,788
Less valuation allowance	(146,861)	(136,008)
Net deferred tax assets	630,822	789,780
Deferred tax liabilities
Deferred tax on undistributed foreign earnings	(5,000)	(5,000)
Accumulated depreciation, depletion and amortization	(847,981)	(796,510)
Other deferred tax liabilities	(54,052)	(85,284)
Total gross deferred tax liabilities	(907,033)	(886,794)
Net deferred tax (liabilities) assets	$ (276,211)	$ (97,014)