Business Concentration - Additional Information (Detail)	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2012
Number of customer	12	25
ECOTRAX rail ties
Concentration risk percentage	73.00%	65.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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