Changes in Standardized Measure of Discounted Future Net Cash Flows (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Standardized measure of discounted future net cash flows, beginning of year	$ 6,154,648	$ 7,033,189
Sales of oil and gas, net of production costs and taxes	(1,190,850)	(1,359,448)
Purchases of reserves in place	0	0
Sales of reserves in place		(160,748)
Changes in development costs	98,054	(7,872)
Revisions of previous estimates	213,112	(524,565)
Changes in prices and production costs	(341,335)	492,325
Net changes in income taxes	440,034	(21,553)
Accretion of discount	615,465us-gaap_AccretionOfDiscount	703,319us-gaap_AccretionOfDiscount
Standardized measure of discounted future net cash flows, end of year	$ 7,142,460	$ 6,154,648

Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of passage of time.

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Amount of decrease in standardized measure of discounted future net cash flow as a result of sales of minerals in place.

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Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of change in estimated future development costs.

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Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of change in the estimated future income tax on future pretax net cash flows related to the entity's proved oil and gas reserves.

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Amount of increase in standardized measure of discounted future net cash flow as a result of purchases of minerals in place.

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Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of change in sales and transfer prices and in production (lifting) costs related to future production.

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Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of revisions of estimated quantity of oil and gas in proved reserves.

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Amount of (increase) decrease in standardized measure of discounted future net cash flow as a result of sales and transfers of oil and gas produced.

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Amount of discounted future accumulated cash inflow relating to proved oil and gas reserves.

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