Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 76,023	$ 90,635
Trade accounts and other receivables, net	109,828	103,258
Inventories:
Finished goods	100,274	102,625
Raw materials and supplies	42,131	38,061
Total inventories	142,405	140,686
Prepaid expenses and other current assets	7,731	4,293
Prepaid income taxes	3,049
Deferred income taxes	11,022	11,045
Total current assets	350,058	349,917
Property, plant and equipment:
Land and land improvements	19,758	19,700
Land-use and mineral rights	11,149	9,559
Buildings	68,856	67,866
Machinery and equipment	534,258	530,129
Construction in progress	59,593	39,564
Total	693,614	666,818
Less accumulated depreciation and amortization	260,373	240,586
Net property, plant and equipment	433,241	426,232
Goodwill	12,164	12,164
Intangible and other assets, net	18,509	20,565
Total assets	813,972	808,878
Current liabilities:
Accounts payable	15,333	20,078
Accrued income taxes		727
Other accrued expenses	23,394	30,025
Total current liabilities	38,727	50,830
Deferred income taxes	46,582	44,970
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; 23,083,033 and 23,092,906 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively	231	231
Additional paid-in capital	54,329	57,364
Retained earnings	677,816	657,423
Accumulated other comprehensive loss	(3,713)	(1,940)
Total shareholders' equity	728,663	713,078
Total liabilities and shareholders' equity	$ 813,972	$ 808,878