CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 46,824	$ 63,769
Short-term investments	270,702	330,553
Accounts receivable	47,303	75,494
Allowance for doubtful accounts	(691)	(699)
Accounts receivable, net	46,612	74,795
Inventories:
Finished goods	22,554	28,893
Raw materials	1,490	1,990
Total inventories	24,044	30,883
Supplies, prepaid items and other:
Prepaid insurance	1,863	17,429
Precious metals	12,544	13,323
Supplies	30,251	27,501
Other	4,409	8,346
Total supplies, prepaid items and other	49,067	66,599
Total current assets	437,249	566,599
Property, plant and equipment, net	828,828	848,661
Other assets:
Operating lease assets	24,621	22,682
Intangible and other assets, net	1,508	1,877
Total other assets	26,129	24,559
Total assets	1,292,206	1,439,819
Current liabilities:
Accounts payable	56,796	78,182
Short-term financing		16,134
Accrued and other liabilities	37,395	38,470
Current portion of long-term debt	5,493	9,522
Total current liabilities	99,684	142,308
Long-term debt, net	577,173	702,733
Noncurrent operating lease liabilities	15,713	14,896
Other noncurrent accrued and other liabilities	522	522
Deferred income taxes	66,370	63,487
Commitments and contingencies (Note 5)
Stockholders' equity:
Common stock, $.10 par value; 150 million shares authorized, 91.2 million shares issued	9,117	9,117
Capital in excess of par value	499,528	497,179
Retained earnings	232,362	199,092
Stockholders equity including treasury stock	741,007	705,388
Less treasury stock, at cost:
Common stock, 16.8 million shares (14.9 million shares at December 31, 2022)	208,263	189,515
Total stockholders' equity	532,744	515,873
Total Liabilities and Stockholders' equity	$ 1,292,206	$ 1,439,819