Gains on Dispositions of Plant, Equipment and Timberlands, Net - Summary for Sale of Timberlands and Other Assets (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) a	Sep. 30, 2014 USD ($) a
Property, Plant and Equipment [Line Items]
Proceeds			$ 3,181	$ 4,051
Gain	$ 123	$ 1,590	$ 2,888	$ 3,881
Timberlands [Member]
Property, Plant and Equipment [Line Items]
Acres | a			1,398	2,030
Proceeds			$ 2,794	$ 4,041
Gain			2,704	3,876
Other [Member]
Property, Plant and Equipment [Line Items]
Proceeds			387	10
Gain			$ 184	$ 5