Goodwill - gross goodwill balance and accumulated impairment loss (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill, gross
Total goodwill, gross	$ 16,881,416us-gaap_GoodwillGross	$ 16,993,121us-gaap_GoodwillGross
Accumulated impairment loss
Total accumulated impairment loss	(725,744)	(725,744)
Goodwill, net	16,155,672us-gaap_Goodwill	16,267,377us-gaap_Goodwill	14,891,377us-gaap_Goodwill
Natural Gas Operations [Member]
Goodwill, gross
Total goodwill, gross	14,779,672	14,891,377
Accumulated impairment loss
Total accumulated impairment loss	0	0
Goodwill, net	14,779,672	14,891,377	14,891,377
Marketing And Production Operations [Member]
Goodwill, gross
Total goodwill, gross	2,101,744	2,101,744
Accumulated impairment loss
Total accumulated impairment loss	(725,744)	(725,744)
Goodwill, net	$ 1,376,000	$ 1,376,000	$ 0

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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- Definition

Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a,h)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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