CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 254,299	$ 82,144
Short-term investments	89,311
Accounts receivable	97,515	86,902
Allowance for doubtful accounts	(463)	(474)
Accounts receivable, net	97,052	86,428
Inventories:
Finished goods	25,810	14,688
Raw materials	1,590	1,895
Total inventories	27,400	16,583
Supplies, prepaid items and other:
Prepaid insurance	10,557	14,244
Precious metals	13,945	14,945
Supplies	27,066	26,558
Other	9,805	2,234
Total supplies, prepaid items and other	61,373	57,981
Total current assets	529,435	243,136
Property, plant and equipment, net	850,372	858,480
Other assets:
Operating lease assets	24,829	27,317
Intangible and other assets, net	3,555	3,907
Total other assets	28,384	31,224
Total assets	1,408,191	1,132,840
Current liabilities:
Accounts payable	60,649	49,458
Short-term financing	9,911	12,716
Accrued and other liabilities	44,913	33,301
Current portion of long-term debt	8,112	9,454
Total current liabilities	123,585	104,929
Long-term debt, net	708,398	518,190
Noncurrent operating lease liabilities	17,542	19,568
Other noncurrent accrued and other liabilities	3,023	3,030
Deferred income taxes	37,455	26,633
Commitments and contingencies (Note 6)
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	493,964	493,161
Retained earnings (accumulated deficit)	27,511	(31,255)
Stockholders equity including treasury stock	530,592	471,023
Less treasury stock, at cost:
Common stock, 1.6 million shares (1.4 million shares at December 31, 2021)	12,404	10,533
Total stockholders' equity	518,188	460,490
Total Liabilities and Stockholders' equity	$ 1,408,191	$ 1,132,840