Condensed Consolidating Financial Statements - Condensed Consolidating Statement of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Income Statements, Captions [Line Items]
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) losses on dispositions of plant, equipment and timberlands, net	(249)	(93)	(1,939)	(168)
Operating income (loss)	4,322	10,385	19,757	23,890
Other 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 (benefit)	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
Other comprehensive income (loss)	19,971	17,330	8,338	50,855
Comprehensive income (loss)	(75,860)	29,435	(89,174)	68,849
Adjustments/ Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	$ (29,340)	$ (21,799)	$ (79,435)	$ (64,064)
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Costs of products sold	$ (29,340)	$ (21,799)	$ (79,435)	$ (64,064)
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Other non-operating income (expense)
Interest expense	$ 1,549	$ 1,430	$ 4,526	$ 4,049
Interest income	(1,549)	(1,430)	(4,526)	(4,049)
Equity in earnings of subsidiaries	(24,000)	(35,976)	(95,166)	(101,495)
Total non-operating expense	(24,000)	(35,976)	(95,166)	(101,495)
Income (loss) before income taxes	(24,000)	(35,976)	(95,166)	(101,495)
Income (loss) from continuing operations	(24,000)	(35,976)	(95,166)	(101,495)
Discontinued operations:
Net income (loss)	(24,000)	(35,976)	(95,166)	(101,495)
Other comprehensive income (loss)	4,954	(29,771)	38,619	(87,222)
Comprehensive income (loss)	$ (19,046)	$ (65,747)	$ (56,547)	$ (188,717)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Costs of products sold	$ 945	$ 1,596	$ 4,254	$ 1,223
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Gross profit (loss)	$ (945)	$ (1,596)	$ (4,254)	$ (1,223)
Selling, general and administrative expenses	10,557	12,414	35,457	37,022
(Gains) losses on dispositions of plant, equipment and timberlands, net		1	(17)
Operating income (loss)	(11,502)	(14,011)	(39,694)	(38,245)
Other non-operating income (expense)
Interest expense	(4,439)	(4,018)	(12,773)	(12,078)
Interest income	134	160	413	451
Equity in earnings of subsidiaries	13,217	17,880	49,421	50,298
Other, net	341	589	(1,634)	1,873
Total non-operating expense	9,253	14,611	35,427	40,544
Income (loss) before income taxes	(2,249)	600	(4,267)	2,299
Income tax provision (benefit)	(1,544)	(4,445)	(7,108)	(6,788)
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
Other comprehensive income (loss)	19,971	17,330	8,338	50,855
Comprehensive income (loss)	(75,860)	29,435	(89,174)	68,849
Guarantors [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	$ 35,285	$ 20,588	$ 87,617	$ 63,173
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Costs of products sold	$ 32,727	$ 19,525	$ 82,089	$ 60,158
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Gross profit (loss)	$ 2,558	$ 1,063	$ 5,528	$ 3,015
Selling, general and administrative expenses	43	536	1,716	846
(Gains) losses on dispositions of plant, equipment and timberlands, net	(249)	(114)	(1,929)	(188)
Operating income (loss)	2,764	641	5,741	2,357
Other non-operating income (expense)
Interest expense	(629)	(300)	(1,670)	(619)
Interest income	1,528	1,316	4,219	3,714
Equity in earnings of subsidiaries	10,783	18,096	45,745	51,197
Other, net	1,077	(1,920)	(1,657)	(6,445)
Total non-operating expense	12,759	17,192	46,637	47,847
Income (loss) before income taxes	15,523	17,833	52,378	50,204
Income tax provision (benefit)	2,349	(47)	3,022	(94)
Income (loss) from continuing operations	13,174	17,880	49,356	50,298
Discontinued operations:
Net income (loss)	13,174	17,880	49,356	50,298
Other comprehensive income (loss)	(1,767)	14,812	(19,318)	43,878
Comprehensive income (loss)	11,407	32,692	30,038	94,176
Non Guarantors [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	$ 203,910	$ 211,331	$ 628,624	$ 591,926
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Costs of products sold	$ 175,651	$ 173,423	$ 530,165	$ 488,466
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Gross profit (loss)	$ 28,259	$ 37,908	$ 98,459	$ 103,460
Selling, general and administrative expenses	15,199	14,133	44,742	43,662
(Gains) losses on dispositions of plant, equipment and timberlands, net		20	7	20
Operating income (loss)	13,060	23,755	53,710	59,778
Other non-operating income (expense)
Interest expense	(446)	(436)	(1,320)	(1,377)
Interest income	34	5	121	93
Other, net	835	944	4,422	4,014
Total non-operating expense	423	513	3,223	2,730
Income (loss) before income taxes	13,483	24,268	56,933	62,508
Income tax provision (benefit)	2,657	6,172	11,123	11,311
Income (loss) from continuing operations	10,826	18,096	45,810	51,197
Discontinued operations:
Net income (loss)	10,826	18,096	45,810	51,197
Other comprehensive income (loss)	(3,187)	14,959	(19,301)	43,344
Comprehensive income (loss)	$ 7,639	$ 33,055	$ 26,509	$ 94,541