Condensed Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements of Income [Abstract]
Net sales	$ 416,493	$ 379,097	$ 1,211,249	$ 1,079,153
Energy and related sales - net	2,840	3,312	7,887	8,834
Total revenues	419,333	382,409	1,219,136	1,087,987
Costs of products sold	364,417	326,669	1,066,553	952,571
Gross profit	54,916	55,740	152,583	135,416
Selling, general and administrative expenses	31,430	27,782	94,520	91,299
Gains on dispositions of plant, equipment and timberlands, net	(698)	(150)	(3,902)	(318)
Operating income	24,184	28,108	61,965	44,435
Other non-operating income (expense)
Interest expense	(6,456)	(6,565)	(19,377)	(19,045)
Interest income	134	232	491	570
Other - net	(137)	(251)	(405)	(3,868)
Total other non-operating expense	(6,459)	(6,584)	(19,291)	(22,343)
Income (loss) before income taxes	17,725	21,524	42,674	22,092
Income tax provision (benefit)	4,699	(17,913)	9,721	(17,074)
Net income (loss)	$ 13,026	$ 39,437	$ 32,953	$ 39,166
Earnings (loss) per share
Basic	$ 0.29	$ 0.86	$ 0.72	$ 0.85
Diluted	$ 0.28	$ 0.85	$ 0.71	$ 0.85
Cash dividends declared per common share	$ 0.09	$ 0.09	$ 0.27	$ 0.27
Weighted average shares outstanding
Basic	45,299	45,950	45,813	45,898
Diluted	45,839	46,286	46,341	46,330