CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 60,749	$ 68,169
Restricted cash	5,528	6,935
Trade accounts and other receivables, net	35,464	37,705
Inventories:
Finished goods	53,574	59,519
Raw materials and supplies	20,450	19,480
Total inventories	74,024	78,999
Prepaid expenses and other current assets	5,393	3,989
Total current assets	181,158	195,797
Restricted cash	3,857	3,281
Income tax receivable	2,348	2,389
Property, plant and equipment:
Land and land improvements	41,590	41,590
Land-use and mineral rights	19,696	19,696
Buildings	72,427	72,427
Machinery and equipment	454,543	455,863
Construction in progress	36,148	36,138
Total property, plant and equipment	624,404	625,714
Less accumulated depreciation and amortization	308,720	301,528
Net property, plant and equipment	315,684	324,186
Goodwill	3,500	3,500
Intangible and other assets, net	10,631	11,445
Total assets	517,178	540,598
Current liabilities:
Accounts payable	20,469	19,417
Accrued payroll and benefits	3,789	6,056
Accrued freight	1,874	2,292
Accrued utilities	905	1,552
Derivative instruments	1,933	2,537
Other accrued expenses	10,942	10,577
Total current liabilities	39,912	42,431
Deferred income taxes	234	230
Long-term debt, net	60,868	60,698
Notes payable, related parties	27,040	27,040
Other long-term liabilities	5,149	4,434
Shareholders' equity:
Preferred stock, par value $0.01 per share, 5,000 shares authorized, none outstanding
Common stock, par value $0.01 per share, 80,000,000 shares authorized; 27,413,293 and 27,133,614 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	274	271
Additional paid-in capital	126,615	125,715
Retained earnings	257,086	279,779
Total shareholders' equity	383,975	405,765
Total liabilities and shareholders' equity	$ 517,178	$ 540,598