Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales	$ 229,133	$ 211,207
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember
Costs of products sold	$ 193,516	$ 174,647
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember
Gross profit	$ 35,617	$ 36,560
Selling, general and administrative expenses	24,622	29,931
Gains on dispositions of plant, equipment and timberlands, net	(669)	(1,116)
Operating income	11,664	7,745
Non-operating income (expense)
Interest expense	(4,746)	(3,450)
Interest income	505	54
Other, net	(962)	(323)
Total non-operating expense	(5,203)	(3,719)
Income from continuing operations before income taxes	6,461	4,026
Income tax provision	1,858	1,762
Income from continuing operations	4,603	2,264
Discontinued operations:
Income before income taxes	714	4,459
Income tax provision	31	1,007
Income from discontinued operations	683	3,452
Net income	$ 5,286	$ 5,716
Basic earnings per share
Income from continuing operations	$ 0.10	$ 0.05
Income from discontinued operations	0.02	0.08
Basic earnings per share	0.12	0.13
Diluted earnings per share
Income from continuing operations	0.10	0.05
Income from discontinued operations	0.02	0.08
Diluted earnings per share	0.12	0.13
Cash dividends declared per common share	$ 0.13	$ 0.13
Weighted average shares outstanding
Basic	44,027	43,700
Diluted	44,279	44,567