CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 96,143	$ 24,298
Trade accounts and other receivables, net	68,713	132,573
Inventories:
Finished goods	105,632	106,941
Raw materials and supplies	23,664	37,502
Total inventories	129,296	144,443
Prepaid expenses and other current assets	4,530	5,241
Prepaid income taxes	2,632	19,708
Deferred income taxes	26,271	11,348
Total current assets	327,585	337,611
Property, plant and equipment:
Land and land improvements	40,888	40,921
Land-use and mineral rights	19,877	19,877
Buildings	75,263	74,911
Machinery and equipment	625,370	627,517
Construction in progress	128,351	109,378
Total	889,749	872,604
Less accumulated depreciation and amortization	314,271	303,888
Net property, plant and equipment	575,478	568,716
Goodwill	12,164	12,164
Intangible and other assets, net	24,286	15,735
Total assets	939,513	934,226
Current liabilities:
Bank borrowings	75,000	25,000
Accounts payable	13,028	22,922
Accrued payroll and benefits	2,766	12,466
Accrued freight	1,155	5,925
Accrued utilities	1,768	3,714
Dividends payable	2,327
Derivative instruments	6,759
Other accrued expenses	12,155	7,388
Total current liabilities	114,958	77,415
Deferred income taxes	81,631	80,754
Derivative instruments	5,788
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; 23,271,763 and 23,092,674 shares issued and outstanding at March 31, 2015 and December 31, 2014, respectively	233	231
Additional paid-in capital	59,937	59,297
Retained earnings	700,337	739,498
Accumulated other comprehensive loss	(23,371)	(22,969)
Total shareholders' equity	737,136	776,057
Total liabilities and shareholders' equity	$ 939,513	$ 934,226