Supplemental Information On Oil And Gas Exploration And Production Activities (Unaudited) - Changes in Quantities of Proved Oil and natural Gas Reserves (Details)	12 Months Ended
Dec. 31, 2015 MBoe MBbls MMcf	Dec. 31, 2014 MBoe MBbls MMcf	Dec. 31, 2013 MBoe MBbls MMcf	Dec. 31, 2012 MBoe MBbls MMcf
Reserve Quantities [Line Items]
Beginning balance \| MBoe	22,192	11,431	2,594
Extensions and discoveries \| MBoe	685	2,364	4,812
Sale of minerals in place \| MBoe	(1,344)		(15)
Purchases of minerals in place \| MBoe	1,962	8,473	2,382
Production \| MBoe	(1,437)	(882)	(737)
Revision to previous estimates \| MBoe	(9,484)	806	2,395
Ending Balance \| MBoe	12,574	22,192	11,431
Proved developed reserves \| MBoe	8,613	9,800	3,706	1,938
Proved undeveloped reserves \| MBoe	3,961	12,392	7,725	9,493
Crude Oil [Member]
Reserve Quantities [Line Items]
Beginning balance	13,803	6,078	519
Extensions and discoveries	526	1,909	3,586
Sale of minerals in place	(4)		(15)
Purchases of minerals in place	1,641	7,025	2,051
Production	(904)	(403)	(163)
Revision to previous estimates	(5,701)	(806)	100
Ending balance	9,361	13,803	6,078
Proved developed reserves	6,114	6,093	1,307	296
Proved undeveloped reserves	3,247	7,710	4,771	5,782
Natural Gas [Member]
Reserve Quantities [Line Items]
Beginning balance \| MMcf	38,579	24,213	10,099
Extensions and discoveries \| MMcf	828	1,403	4,198
Sale of minerals in place \| MMcf	(8,040)
Purchases of minerals in place \| MMcf	679	6,064	709
Production \| MMcf	(2,143)	(2,132)	(2,635)
Revision to previous estimates \| MMcf	(16,565)	9,031	11,842
Ending Balance \| MMcf	13,338	38,579	24,213
Proved developed reserves \| MMcf	10,954	16,214	11,053	8,245
Proved undeveloped reserves \| MMcf	2,384	22,365	13,160	15,968
Natural Gas Liquids
Reserve Quantities [Line Items]
Beginning balance	1,959	1,318	392
Extensions and discoveries	21	221	526
Purchases of minerals in place	208	437	213
Production	(176)	(124)	(134)
Revision to previous estimates	(1,022)	107	321
Ending balance	990	1,959	1,318
Proved developed reserves	673	1,005	557	268
Proved undeveloped reserves	317	954	761	1,050

Proved Developed And Undeveloped Reserves Extensions Discoveries And Additions Gas

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Proved Developed And Undeveloped Reserves Net Gas

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Proved Developed And Undeveloped Reserves Purchases Of Minerals In Place Gas

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Proved Developed And Undeveloped Reserves Revisions Of Previous Estimates Increase Decrease Gas

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Proved Developed And Undeveloped Reserves Sales Of Minerals In Place Gas

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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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Energy measure of proved reserve of oil and gas, 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 production, 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 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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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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Additions to proved reserves that result from (1) extension of the proved acreage of previously discovered (old) reservoirs through additional drilling in periods after discovery and (2) discovery of new fields with proved reserves or of new reservoirs of proved reserves in old fields.

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The net quantity of proved reserves as of the balance sheet date. Proved oil reserves are the estimated quantities of crude oil and natural gas liquids which geological and engineering data demonstrate with reasonable certainty to be recoverable.

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Production of proved reserves.

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Purchase of minerals in place.

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Revisions represent changes in previous estimates of proved reserves, either upward or downward, resulting from new information (except for an increase in proved acreage) normally obtained from development drilling and production history or resulting from change in economic factors.

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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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Sales of minerals in place.

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Energy measure of interests in proved developed reserves of crude oil, including condensate and natural gas liquids, natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas.

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Net quantities of an enterprise's interests in proved developed reserves of either crude oil (including condensate and natural gas liquids), natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas as of the beginning and the end of the year. "Net" quantities of reserves include those relating to the enterprise's operating and nonoperating interests in properties. Quantities of reserves relating to royalty interests owned are included in "net" quantities if the necessary information is available to the enterprise. "Net" quantities does not include reserves relating to interests of others in properties owned by the enterprise. The unit of measure for reserve quantities is defined as "barrels" for oil and synthetic oil reserves or "cubic feet" or "cubic meters" for natural gas and synthetic gas reserves.

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Energy measure of proved undeveloped reserves of crude oil, including condensate and natural gas liquids, natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas.

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Net quantities of an enterprise's interests in proved undeveloped reserves of either crude oil (including condensate and natural gas liquids), natural gas, synthetic oil and gas, or other renewable natural resource that is intended to be upgraded into synthetic oil and gas as of the beginning and the end of the year. "Net" quantities of reserves include those relating to the enterprise's operating and nonoperating interests in properties. Quantities of reserves relating to royalty interests owned are included in "net" quantities if the necessary information is available to the enterprise. "Net" quantities does not include reserves relating to interests of others in properties owned by the enterprise. The unit of measure for reserve quantities is defined as "barrels" for oil and synthetic oil reserves or "cubic feet" or "cubic meters" for natural gas and synthetic gas reserves.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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