Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
Jun. 30, 2007	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]
Company made payments to Lower Willamette Group as interim settlement	$ 175,000
Maximum amount anticipated to spend for further Source Control work		100,000
Adjustment related to contingency liability in Portland Harbor matters		0
Total stand by letters of credit		$ 3,100,000

Amount anticipated to spent for further source control work.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

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- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

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- Definition

Amount of increase (decrease) in loss contingency liability.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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