Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Net sales	$ 235,053	$ 215,742	$ 464,186	$ 426,949
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Costs of products sold	$ 197,553	$ 182,443	$ 391,069	$ 357,090
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Gross profit	$ 37,500	$ 33,299	$ 73,117	$ 69,859
Selling, general and administrative expenses	22,800	26,185	47,422	56,116
Gains on dispositions of plant, equipment and timberlands, net	(423)	(574)	(1,092)	(1,690)
Operating income	15,123	7,688	26,787	15,433
Non-operating income (expense)
Interest expense	(1,865)	(3,822)	(6,611)	(7,272)
Interest income	241	26	746	80
Other, net	(1,551)	(799)	(2,513)	(1,122)
Total non-operating expense	(3,175)	(4,595)	(8,378)	(8,314)
Income from continuing operations before income taxes	11,948	3,093	18,409	7,119
Income tax provision	5,655	1,813	7,513	3,575
Income from continuing operations	6,293	1,280	10,896	3,544
Discontinued operations:
Income (loss) before income taxes	(485)	(18,517)	229	(14,058)
Income tax provision (benefit)	(23)	(9,838)	8	(8,831)
Income (loss) from discontinued operations	(462)	(8,679)	221	(5,227)
Net income (loss)	$ 5,831	$ (7,399)	$ 11,117	$ (1,683)
Basic earnings per share
Income from continuing operations	$ 0.14	$ 0.03	$ 0.25	$ 0.08
Income (loss) from discontinued operations	(0.01)	(0.20)	0.01	(0.12)
Basic earnings (loss) per share	0.13	(0.17)	0.26	(0.04)
Diluted earnings (loss) per share
Income from continuing operations	0.14	0.03	0.25	0.08
Income (loss) from discontinued operations	(0.01)	(0.20)		(0.12)
Diluted earnings (loss) per share	0.13	(0.17)	0.25	(0.04)
Cash dividends declared per common share	$ 0.13	$ 0.13	$ 0.26	$ 0.26
Weighted average shares outstanding
Basic	44,140	43,770	44,084	43,735
Diluted	44,382	44,487	44,351	44,531