CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 21,705	$ 26,048
Accounts receivable	46,524	67,043
Allowance for doubtful accounts	(475)	(351)
Accounts receivable, net	46,049	66,692
Inventories:
Finished goods	30,301	27,726
Raw materials	2,239	1,483
Total inventories	32,540	29,209
Supplies, prepaid items and other:
Prepaid insurance	7,933	10,924
Supplies	25,276	24,576
Other	8,002	8,964
Total supplies, prepaid items and other	41,211	44,464
Total current assets	141,505	166,413
Property, plant and equipment, net	962,538	974,248
Other assets:
Operating lease assets	15,317
Intangible and other assets, net	7,109	7,672
Total other assets	22,426	7,672
Total Assets	1,126,469	1,148,333
Current liabilities:
Accounts payable	49,898	62,589
Short-term financing	5,863	8,577
Accrued and other liabilities	37,671	42,129
Current portion of long-term debt	12,275	12,518
Total current liabilities	105,707	125,813
Long-term debt, net	412,913	412,681
Noncurrent operating lease liabilities	9,671
Other noncurrent accrued and other liabilities	8,373	8,861
Deferred income taxes	57,057	56,612
Commitments and contingencies (Note 6)
Stockholders' equity:
Common stock, $.10 par value; 75,000,000 shares authorized, 31,283,210 shares issued	3,128	3,128
Capital in excess of par value	198,950	198,482
Retained earnings	134,481	153,773
Stockholders equity including treasury stock	339,559	358,383
Less treasury stock, at cost:
Common stock, 2,513,575 shares (2,438,305 shares at December 31, 2018)	16,732	16,186
Total stockholders' equity	322,827	342,197
Total Liabilities and Stockholders' equity	1,126,469	1,148,333
Series E Preferred Stock [Member]
Redeemable preferred stocks:
Redeemable preferred stock, value	209,921	202,169
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