Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current Assets:
Cash and Cash Equivalents	$ 172,551	$ 199,371
Short-Term Investments	82,583	81,932
Accounts and Notes Receivable
Trade Receivables, net	163,544	147,612
Other Receivables, net	16,457	12,765
Inventories	109,490	88,154
Other Current Assets	69,088	71,172
Total Current Assets	613,713	601,006
Property, Plant and Equipment:
Property, Plant and Equipment	5,594,414	5,552,404
Less - Accumulated Depreciation, Depletion and Amortization	3,699,743	3,649,281
Total Property, Plant and Equipment—Net	1,894,671	1,903,123
Other Assets:
Right of Use Asset - Operating Leases	13,442	14,658
Salary Retirement	48,809	47,246
Other Noncurrent Assets, net	109,489	108,970
Total Other Assets	171,740	170,874
TOTAL ASSETS	2,680,124	2,675,003
Current Liabilities:
Accounts Payable	139,301	137,243
Current Portion of Long-Term Debt	8,549	11,106
Operating Lease Liability, Current Portion	4,468	4,769
Other Accrued Liabilities	264,978	290,606
Total Current Liabilities	417,296	443,724
Long-Term Debt:
Long-Term Debt	181,948	181,885
Finance Lease Obligations	3,523	4,182
Total Long-Term Debt	185,471	186,067
Deferred Credits and Other Liabilities:
Postretirement Benefits Other Than Pensions	206,901	207,908
Pneumoconiosis Benefits	153,983	154,943
Asset Retirement Obligations	211,757	212,621
Workers’ Compensation	39,437	39,144
Salary Retirement	20,769	20,808
Operating Lease Liability	9,517	10,385
Deferred Income Taxes	36,293	36,219
Other Noncurrent Liabilities	9,882	19,742
Total Deferred Credits and Other Liabilities	688,539	701,770
TOTAL LIABILITIES	1,291,306	1,331,561
Stockholders' Equity:
Common Stock, $0.01 Par Value; 62,500,000 Shares Authorized, 29,395,337 Shares Issued and Outstanding at March 31, 2024; 29,910,439 Shares Issued and Outstanding at December 31, 2023	294	299
Capital in Excess of Par Value	536,163	547,861
Retained Earnings	1,001,162	944,342
Accumulated Other Comprehensive Loss	(148,801)	(149,060)
TOTAL EQUITY	1,388,818	1,343,442
TOTAL LIABILITIES AND EQUITY	$ 2,680,124	$ 2,675,003