Condensed Consolidating Financial Statements - Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 84,287	$ 55,444	$ 50,752	$ 105,304
Other current assets	487,208	438,815
Plant, equipment and timberlands, net	856,017	775,898
Other assets	269,282	251,102
Total assets	1,696,794	1,521,259
Liabilities and Shareholders' Equity
Current liabilities	336,013	323,011
Long-term debt	459,025	363,647
Deferred income taxes	65,597	54,995
Other long-term liabilities	125,563	125,780
Total liabilities	986,198	867,433
Shareholders’ equity	710,596	653,826
Total liabilities and shareholders’ equity	1,696,794	1,521,259
Parent Company [Member]
Assets
Cash and cash equivalents	374	5,082	3,658	59,130
Other current assets	226,678	206,002
Plant, equipment and timberlands, net	383,014	360,521
Investments in subsidiaries	885,734	789,565
Other assets	129,617	123,010
Total assets	1,625,417	1,484,180
Liabilities and Shareholders' Equity
Current liabilities	436,791	426,628
Long-term debt	357,441	283,686
Deferred income taxes	14,478	10,221
Other long-term liabilities	106,111	109,819
Total liabilities	914,821	830,354
Shareholders’ equity	710,596	653,826
Total liabilities and shareholders’ equity	1,625,417	1,484,180
Guarantors [Member]
Assets
Cash and cash equivalents	682	1,461	418	465
Other current assets	287,440	256,289
Plant, equipment and timberlands, net	70,093	31,455
Investments in subsidiaries	634,893	540,029
Total assets	993,108	829,234
Liabilities and Shareholders' Equity
Current liabilities	58,602	26,085
Long-term debt	49,000	14,000
Deferred income taxes	(541)	(729)
Other long-term liabilities	313	313
Total liabilities	107,374	39,669
Shareholders’ equity	885,734	789,565
Total liabilities and shareholders’ equity	993,108	829,234
Non Guarantors [Member]
Assets
Cash and cash equivalents	83,231	48,901	$ 46,676	$ 45,709
Other current assets	289,956	242,187
Plant, equipment and timberlands, net	402,910	383,922
Other assets	139,665	128,092
Total assets	915,762	803,102
Liabilities and Shareholders' Equity
Current liabilities	157,486	135,961
Long-term debt	52,584	65,961
Deferred income taxes	51,660	45,503
Other long-term liabilities	19,139	15,648
Total liabilities	280,869	263,073
Shareholders’ equity	634,893	540,029
Total liabilities and shareholders’ equity	915,762	803,102
Adjustments/ Eliminations [Member]
Assets
Other current assets	(316,866)	(265,663)
Investments in subsidiaries	(1,520,627)	(1,329,594)
Total assets	(1,837,493)	(1,595,257)
Liabilities and Shareholders' Equity
Current liabilities	(316,866)	(265,663)
Total liabilities	(316,866)	(265,663)
Shareholders’ equity	(1,520,627)	(1,329,594)
Total liabilities and shareholders’ equity	$ (1,837,493)	$ (1,595,257)