Gains on Dispositions of Plant, Equipment and Timberlands, Net - Summary for Sale of Timberlands and Other Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Property, Plant and Equipment [Line Items]
Proceeds		$ 839
Gain	2,654	809
Timberlands [Member]
Property, Plant and Equipment [Line Items]
Acres	1,370	498
Proceeds	2,726	838
Gain	2,654	812
Other [Member]
Property, Plant and Equipment [Line Items]
Proceeds		1
Gain		$ (3)