CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 39,529	$ 127,314
Accounts receivable, net	87,496	92,602
Inventories:
Finished goods	26,433	24,383
Work in progress	1,893	2,042
Raw materials	20,313	26,812
Total inventories	48,639	53,237
Supplies, prepaid items and other:
Prepaid insurance	7,959	10,563
Precious metals	12,669	12,918
Supplies	20,003	18,681
Prepaid and refundable income taxes	5,954	6,811
Other	4,445	5,797
Total supplies, prepaid items and other	51,030	54,770
Deferred income taxes	4,588	4,774
Total current assets	231,282	332,697
Property, plant and equipment, net	1,087,954	1,005,488
Intangible and other, net	24,060	23,642
Total assets	1,343,296	1,361,827
Current liabilities:
Accounts payable	106,853	108,002
Short-term financing	6,399	9,119
Accrued and other liabilities	42,049	52,331
Current portion of long-term debt	16,836	22,468
Total current liabilities	172,137	191,920
Long-term debt, net	511,678	497,954
Noncurrent accrued and other liabilities	23,754	20,922
Deferred income taxes	$ 50,715	$ 52,179
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock, $.10 par value; 75,000,000 shares authorized, 27,137,599 shares issued (27,131,724 shares at December 31, 2015)	$ 2,714	$ 2,713
Capital in excess of par value	190,378	192,249
Retained earnings	223,616	248,150
Stockholders equity including treasury stock	419,708	446,112
Less treasury stock, at cost:
Common stock, 3,283,081 shares (3,735,503 shares at December 31, 2015)	21,561	24,532
Total stockholders' equity	398,147	421,580
Total Liabilities and Stockholders' equity	1,343,296	1,361,827
Series E Preferred Stock [Member]
Redeemable preferred stocks:
Redeemable preferred stock, value	186,865	177,272
Series B Preferred Stock [Member]
Stockholders' equity:
Preferred stock, value	2,000	2,000
Series D Preferred Stock [Member]
Stockholders' equity:
Preferred stock, value	$ 1,000	$ 1,000