Environmental Settlement and Related Costs - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
Oct. 01, 2014 Charge	Aug. 25, 2014	Dec. 31, 2014
Environmental Remediation Obligations [Abstract]
Fines associated with the Consent Decree amount		$ 3,000,000us-gaap_EnvironmentalRemediationExpense	$ 6,600,000us-gaap_EnvironmentalRemediationExpense
Preliminarily estimated cost of restoration		3,000,000
Maximum cost of restoration		9,000,000
Fine agreed to pay for violation of the Clean Water Act	$ 600,000
Period of probation	2 years
Number of misdemeanor charges to which the company pleaded guilty	3teng_NumberOfCharges

Fines for failure to comply with environmental protection requirements.

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Number Of Charges

+ References

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- Definition

Probationary Period

+ References

No definition available.

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- Definition

Estimate of reasonably possible loss exposure in excess of amount accrued for remediation, site restoration, postclosure, monitoring commitments, or other exit costs associated with the sale, disposal or abandonment of a particular property resulting from unanticipated contamination of the assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

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-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

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- Definition

High-end estimate of the reasonably possible loss exposure in excess of the amount accrued for remediation, site restoration, postclosure, monitoring commitments, or other exit costs associated with the sale, disposal or abandonment of a particular property resulting from unanticipated contamination of the assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 5.Y.Q4)

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-Number Topic 5

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- Definition

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

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