Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Current Assets:
Cash and Cash Equivalents	$ 432,174	$ 408,240
Short-Term Investments (Note 6)	0	51,993
Accounts and Notes Receivable:
Trade Receivables, net	349,233	136,750
Other Receivables, net	53,928	25,900
Inventories (Note 9)	374,759	96,201
Other Current Assets	130,128	66,874
Total Current Assets	1,340,222	785,958
Total Property, Plant and Equipment—Net (Note 10)	4,386,882	1,921,699
Other Assets:
Funds for Asset Retirement Obligations (Note 8)	148,874	12,054
Pension Benefits (Note 15)	49,618	41,938
Other Noncurrent Assets, net	204,457	117,894
Total Other Assets	402,949	171,886
TOTAL ASSETS	6,130,053	2,879,543
Current Liabilities:
Accounts Payable	335,623	143,635
Current Portion of Long-Term Debt (Note 13)	98,328	112,865
Other Accrued Liabilities (Note 12)	404,338	262,184
Total Current Liabilities	838,289	518,684
Long-Term Debt:
Long-Term Debt (Note 13)	317,267	79,524
Finance Lease Obligations (Note 14)	36,893	15,270
Total Long-Term Debt	354,160	94,794
Deferred Credits and Other Liabilities:
Postretirement Benefits Other Than Pensions (Note 15)	186,843	176,251
Pneumoconiosis Benefits (Note 16)	261,201	145,489
Asset Retirement Obligations (Note 8)	496,002	212,178
Workers’ Compensation (Note 16)	70,457	36,051
Pension Benefits (Note 15)	21,111	20,073
Deferred Income Taxes (Note 5)	130,113	49,214
Other Noncurrent Liabilities	93,643	58,562
Total Deferred Credits and Other Liabilities	1,259,370	697,818
TOTAL LIABILITIES	2,451,819	1,311,296
Stockholders’ Equity:
Common Stock, $0.01 Par Value; 125,000,000 Shares Authorized, 50,975,185 Shares Issued and Outstanding at December 31, 2025; 62,500,000 Shares Authorized, 29,407,830 Shares Issued and Outstanding at December 31, 2024	510	294
Capital in Excess of Par Value	2,982,077	540,412
Retained Earnings	818,476	1,162,114
Accumulated Other Comprehensive Loss	(122,829)	(134,573)
TOTAL STOCKHOLDERS' EQUITY	3,678,234	1,568,247
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 6,130,053	$ 2,879,543