CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 41,462	$ 78,866
Trade accounts and other receivables, net	25,038	48,596
Inventories:
Finished goods	84,744	77,537
Raw materials and supplies	23,644	27,021
Total inventories	108,388	104,558
Prepaid expenses and other current assets	3,613	3,762
Income tax receivable	37,569
Deferred income taxes		49,495
Total current assets	216,070	285,277
Property, plant and equipment:
Land and land improvements	45,527	45,774
Land-use and mineral rights	19,696	19,877
Buildings	86,910	83,500
Machinery and equipment	645,599	642,396
Construction in progress	93,334	96,084
Total property, plant and equipment	891,066	887,631
Less accumulated depreciation and amortization	362,450	349,900
Net property, plant and equipment	528,616	537,731
Goodwill	3,500	3,500
Intangible and other assets, net	11,337	9,861
Total assets	759,523	836,369
Current liabilities:
Bank borrowings	12,349	33,000
Accounts payable	6,733	10,709
Accrued payroll and benefits	2,771	6,003
Accrued freight	373	3,068
Accrued utilities	1,729	2,414
Accrued income taxes		139
Derivative instruments	6,010	6,240
Other accrued expenses	12,483	8,717
Total current liabilities	42,448	70,290
Deferred income taxes	39,867	63,858
Long-term portion of bank borrowings	52,651	55,000
Derivative instruments	$ 4,361	$ 4,915
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; 23,476,536 and 23,280,696 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	$ 235	$ 233
Additional paid-in capital	67,311	65,067
Retained earnings	588,909	614,708
Accumulated other comprehensive loss	(36,259)	(37,702)
Total shareholders' equity	620,196	642,306
Total liabilities and shareholders' equity	$ 759,523	$ 836,369