CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Current assets
Cash and cash equivalents	$ 49,708	$ 72,833
Prepaid profit sharing	11,529	0
Inventories	63,648	94,608
Assets held for sale	12,774	14,159
Prepaid insurance	5,546	1,740
Other current assets	21,860	25,899
Total current assets	214,892	264,738
Property, plant and equipment, net	287,546	259,457
Intangibles, net	4,725	5,475
Mining supplies inventory	34,795	0
Deferred income taxes	14,001	14,641
Operating lease right-of-use assets	9,595	9,661
Equity securities	17,696	18,663
Other non-current assets	29,505	25,768
Total assets	661,228	631,687
Current liabilities
Current maturities of long-term debt	9,080	4,179
Asset retirement obligations	8,185	9,747
Accrued payroll	19,863	22,663
Excess funding liability	5,450	0
Other current liabilities	10,299	8,752
Total current liabilities	69,615	64,888
Long-term debt	16,815	25,335
Long-term revolving credit agreement	75,000	70,000
Operating lease liabilities	7,950	9,042
Asset retirement obligations	39,516	39,780
Retirement benefit plans	4,558	4,787
Other long-term liabilities	18,531	12,908
Total liabilities	231,985	226,740
Common stock:
Capital in excess of par value	42,427	34,340
Retained earnings	381,130	373,363
Accumulated other comprehensive loss	(1,741)	(10,052)
Total stockholders’ equity	429,243	404,947
Total liabilities and equity	661,228	631,687
Unconsolidated Subsidiaries
Current assets
Equity method investments	14,750	14,137
Equity method investment in Eiger Resources	14,750	14,137
Eiger, LLC
Current assets
Equity method investments	33,723	19,147
Equity method investment in Eiger Resources	33,723	19,147
Nonrelated Party
Current assets
Trade accounts receivable and accounts receivable from affiliates	42,921	49,706
Current liabilities
Accounts payable and accounts payable to affiliates	16,060	17,721
Affiliated Entity
Current assets
Trade accounts receivable and accounts receivable from affiliates	6,906	5,793
Current liabilities
Accounts payable and accounts payable to affiliates	678	1,826
Class A Common Stock
Common stock:
Common stock	5,864	5,730
Class B Common Stock
Common stock:
Common stock	$ 1,563	$ 1,566