CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 55,591	$ 91,680
Restricted cash	5,503
Trade accounts and other receivables, net	29,429	23,622
Inventories:
Finished goods	71,813	74,133
Raw materials and supplies	20,025	23,041
Total inventories	91,838	97,174
Prepaid expenses and other current assets	4,211	3,548
Income tax receivable	2,633	1,199
Total current assets	189,205	217,223
Restricted cash	6,289
Property, plant and equipment:
Land and land improvements	45,534	45,530
Land-use and mineral rights	19,696	19,696
Buildings	87,713	87,318
Machinery and equipment	648,242	647,753
Construction in progress	92,932	92,704
Total property, plant and equipment	894,117	893,001
Less accumulated depreciation and amortization	410,914	398,898
Net property, plant and equipment	483,203	494,103
Goodwill	3,500	3,500
Intangible and other assets, net	9,106	8,631
Total assets	691,303	723,457
Current liabilities:
Long-term debt, current portion		13,000
Accounts payable	6,298	7,782
Accrued payroll and benefits	2,595	3,434
Derivative instruments	2,135	1,599
Other accrued expenses	10,390	8,989
Total current liabilities	21,418	34,804
Deferred income taxes	2,290	1,236
Long-term debt, net	47,957	42,404
Notes payable, related parties	25,000	25,000
Other long-term liabilities	4,006	3,443
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; 27,139,979 and 26,881,066 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	271	269
Additional paid-in capital	122,511	117,192
Retained earnings	500,472	533,435
Accumulated other comprehensive loss	(32,622)	(34,326)
Total shareholders' equity	590,632	616,570
Total liabilities and shareholders' equity	$ 691,303	$ 723,457