Condensed Consolidating Financial Statements - Condensed Consolidating Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Condensed Income Statements, Captions [Line Items]
Net sales	$ 417,469	$ 455,721
Energy and related sales, net	2,068	5,262
Total revenues	419,537	460,983
Costs of products sold	367,429	405,943
Gross profit	52,108	55,040
Selling, general and administrative expenses	31,272	33,551
Gains on dispositions of plant, equipment and timberlands, net	(2,654)	(809)
Operating income	23,490	22,298
Other non-operating income (expense)
Interest expense	(4,508)	(4,812)
Interest income	65	61
Other, net	(187)	211
Total non-operating expense	(4,630)	(4,540)
Income before income taxes	18,860	17,758
Income tax provision	4,935	3,110
Net income	13,925	14,648
Other comprehensive income (loss)	(35,285)	2,965
Comprehensive income	(21,360)	17,613
Adjustments/ Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Net sales		(18)
Total revenues		(18)
Costs of products sold		(18)
Other non-operating income (expense)
Interest expense	6,703	2,658
Interest income	(6,702)	(2,658)
Equity in earnings of subsidiaries	(25,838)	(42,961)
Other, net	(1)
Total non-operating expense	(25,838)	(42,961)
Income before income taxes	(25,838)	(42,961)
Net income	(25,838)	(42,961)
Other comprehensive income (loss)	(298)	(886)
Comprehensive income	(26,136)	(43,847)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	219,876	225,831
Energy and related sales, net	2,068	5,262
Total revenues	221,944	231,093
Costs of products sold	202,519	216,716
Gross profit	19,425	14,377
Selling, general and administrative expenses	17,182	17,793
Gains on dispositions of plant, equipment and timberlands, net	(1,471)	(812)
Operating income	3,714	(2,604)
Other non-operating income (expense)
Interest expense	(4,817)	(4,739)
Interest income	163	153
Equity in earnings of subsidiaries	16,363	22,499
Other, net	(715)	(881)
Total non-operating expense	10,994	17,032
Income before income taxes	14,708	14,428
Income tax provision	783	(220)
Net income	13,925	14,648
Other comprehensive income (loss)	(35,285)	2,965
Comprehensive income	(21,360)	17,613
Guarantors [Member]
Condensed Income Statements, Captions [Line Items]
Net sales		18
Total revenues		18
Costs of products sold		17
Gross profit		1
Selling, general and administrative expenses	190	13
Gains on dispositions of plant, equipment and timberlands, net	(1,183)
Operating income	993	(12)
Other non-operating income (expense)
Interest income	6,599	2,559
Equity in earnings of subsidiaries	9,475	20,462
Other, net	(126)	10
Total non-operating expense	15,948	23,031
Income before income taxes	16,941	23,019
Income tax provision	904	913
Net income	16,037	22,106
Other comprehensive income (loss)	(38,550)	1
Comprehensive income	(22,513)	22,107
Non Guarantors [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	197,593	229,890
Total revenues	197,593	229,890
Costs of products sold	164,910	189,228
Gross profit	32,683	40,662
Selling, general and administrative expenses	13,900	15,745
Gains on dispositions of plant, equipment and timberlands, net		3
Operating income	18,783	24,914
Other non-operating income (expense)
Interest expense	(6,394)	(2,731)
Interest income	5	7
Other, net	655	1,082
Total non-operating expense	(5,734)	(1,642)
Income before income taxes	13,049	23,272
Income tax provision	3,248	2,417
Net income	9,801	20,855
Other comprehensive income (loss)	38,848	885
Comprehensive income	$ 48,649	$ 21,740