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Supplemental Oil and Gas Reserve Information - Unaudited - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Mar. 31, 2014 MBoe	Dec. 31, 2015 location MBoe $ / bbl $ / MMBTU	Dec. 31, 2014 location MBoe $ / bbl $ / MMBTU	Dec. 31, 2013 MBoe $ / bbl $ / MMBTU
Oil and Gas Exploration and Production Industries Disclosures [Abstract]
Purchases of reserves in place (Energy)		2,565	1,799	45,731
Additions due to extensions and discoveries (Energy)		46,640	92,596	46,094
Estimated extensions and discoveries of reserves associated with new wells (Energy)		20,362	34,404	22,190
Percentage of reserves produced from wells in certain formations		100.00%	100.00%	100.00%
Additional proved undeveloped reserves (Energy)		26,278	58,192	23,904
Percentage of proved undeveloped reserves		100.00%	100.00%	100.00%
Divested reserves associated with non-operated properties (Energy)	8,448	0	8,448	0
Net positive (negative) revisions of previous estimates (Energy)		(84,635)	(25,117)	5,125
Percentage of net positive (negative) revisions		(31.00%)	(11.00%)	4.00%
Proved undeveloped locations | location		259	80
Proved undeveloped locations, net | location		190.8	56.2
Proved undeveloped reserves, decrease (Energy)		71,945	21,411
Discount rate of future cash flows		10.00%
Unweighted arithmetic average first-day-of-the-month prices for oil, price per Bbl | $ / bbl		50.16	95.28	96.96
Unweighted arithmetic average first-day-of-the-month prices for natural gas, price per MMBtu | $ / MMBTU		2.63	4.35	3.66

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Estimated extensions and discoveries of reserves associated with new wells

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Energy measure of increase in quantity of proved reserve of oil and gas resulting from the extension of the proved acreage of previously discovered reservoir or discovery of new field with proved reserve or of new reservoir of proved reserve in old field, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 5
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Energy measure of increase in quantity of proved reserve of oil and gas resulting from purchase of mineral in place, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Energy measure of increase (decrease) in quantity of proved reserve of oil and gas related to revision of a previous estimate resulting from new information, except for an increase in proved acreage, or change in economic factors, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe).

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Energy measure of decrease in quantity of proved reserve of oil and gas resulting from sale of mineral in place, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe).

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