Assets and Liabilities Held for Sale - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014 acre
Summary Of Assets And Liabilities Held For Sale [Line Items]
Assets held for sale	$ 14,301,375
Acres of Land Sold	5,159teng_AreaOfLandSold
Wetzel County West Virginia [Member]
Summary Of Assets And Liabilities Held For Sale [Line Items]
Assets held for sale	$ 14,301,375

Amount classified as other assets attributable to disposal group held for sale or disposed of, expected to be disposed of after one year or the normal operating cycle, if longer.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant