Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 209,855	$ 210,120	$ 636,806	$ 591,035
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Costs of products sold	$ 179,983	$ 172,745	$ 537,073	$ 485,783
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Gross profit (loss)	$ 29,872	$ 37,375	$ 99,733	$ 105,252
Selling, general and administrative expenses	25,799	27,083	81,915	81,530
Gains on dispositions of plant, equipment and timberlands, net	(249)	(93)	(1,939)	(168)
Operating income (loss)	4,322	10,385	19,757	23,890
Non-operating income (expense)
Interest expense	(3,965)	(3,324)	(11,237)	(10,025)
Interest income	147	51	227	209
Other, net	2,253	(387)	1,131	(558)
Total non-operating expense	(1,565)	(3,660)	(9,879)	(10,374)
Income (loss) before income taxes	2,757	6,725	9,878	13,516
Income tax provision	3,462	1,680	7,037	4,429
Income (loss) from continuing operations	(705)	5,045	2,841	9,087
Discontinued operations:
Income (loss) before income taxes	(114,656)	9,661	(128,714)	14,422
Income tax provision (benefit)	(19,530)	2,601	(28,361)	5,515
Income (loss) from discontinued operations	(95,126)	7,060	(100,353)	8,907
Net income (loss)	$ (95,831)	$ 12,105	$ (97,512)	$ 17,994
Basic earnings (loss) per share
Income (loss) from continuing operations	$ (0.02)	$ 0.12	$ 0.06	$ 0.21
Income (loss) from discontinued operations	(2.17)	0.16	(2.29)	0.20
Basic earnings (loss) per share	(2.19)	0.28	(2.23)	0.41
Diluted earnings (loss) per share
Income (loss) from continuing operations	(0.02)	0.11	0.06	0.21
Income (loss) from discontinued operations	(2.17)	0.16	(2.29)	0.20
Diluted earnings (loss) per share	(2.19)	0.27	(2.23)	0.41
Cash dividends declared per common share	$ 0.13	$ 0.13	$ 0.39	$ 0.39
Weighted average shares outstanding
Basic	43,792	43,617	43,754	43,601
Diluted	43,792	44,182	43,754	44,410