Consolidated Statements of Income (Loss) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net sales	$ 927,673	$ 866,286	$ 800,362
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Costs of products sold	$ 780,131	$ 735,879	$ 656,773
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Gross profit	$ 147,542	$ 130,407	$ 143,589
Selling, general and administrative expenses	94,967	111,721	110,534
Gains on dispositions of plant, equipment and timberlands, net	(2,060)	(3,256)	(197)
Operating income	54,635	21,942	33,252
Non-operating income (expense)
Interest expense	(10,408)	(15,609)	(13,317)
Interest income	1,123	559	237
Pension settlement	(75,326)
Other, net	(4,477)	383	(705)
Total non-operating expense	(89,088)	(14,667)	(13,785)
Income (loss) before income taxes	(34,453)	7,275	19,467
Income tax provision (benefit)	(9,242)	7,723	25,079
Loss from continuing operations	(25,211)	(448)	(5,612)
Discontinued operations:
Income (loss) before income taxes	1,284	(207,242)	19,868
Income tax provision (benefit)	(2,386)	(30,086)	6,342
Income (loss) from discontinued operations	3,670	(177,156)	13,526
Net income (loss)	$ (21,541)	$ (177,604)	$ 7,914
Basic earnings (loss) per share
Loss from continuing operations	$ (0.57)	$ (0.01)	$ (0.13)
Income (loss) from discontinued operations	0.08	(4.05)	0.31
Basic earnings (loss) per share	(0.49)	(4.06)	0.18
Diluted earnings (loss) per share
Loss from continuing operations	(0.57)	(0.01)	(0.13)
Income (loss) from discontinued operations	0.08	(4.05)	0.30
Diluted earnings (loss) per share	$ (0.49)	$ (4.06)	$ 0.18
Weighted average shares outstanding
Basic	44,132	43,768	43,609
Diluted	44,132	43,768	44,439