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Gains on Dispositions of Plant, Equipment and Timberlands, Net - Additional Information (Detail) $ in Thousands |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Oct. 09, 2015 USD ($) a | Dec. 31, 2015 USD ($) | Sep. 30, 2015 USD ($) | Sep. 30, 2014 USD ($) | Sep. 30, 2015 USD ($) | Sep. 30, 2014 USD ($)
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Proceeds from sale of timberlands |  |  |  |  | $ 3,181 | $ 4,051
After-tax gain on timberlands |  |  | $ 123 | $ 1,590 | $ 2,888 | $ 3,881
Timber Properties [Member] | Scenario, Forecast [Member] |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
After-tax gain on timberlands |  | $ 9,100 |  |  |  |
Timber Properties [Member] | Subsequent Event [Member] |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |
Acres of timberlands | a | 9,803 |  |  |  |  |
Proceeds from sale of timberlands | $ 17,000 |  |  |  |  |

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- Definition Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 + Details
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- Definition Revenue from sale of timber, mill lumber, wood, and other wood products. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1(a)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
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