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Supplemental Disclosures about Oil and Natural Gas Producing Properties (unaudited) - Estimated Quantities of Proved Oil and Natural Gas Reserves (Details) | 12 Months Ended |
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Jun. 30, 2016 Boe Mcf bbl | Jun. 30, 2015 Boe Mcf bbl | Jun. 30, 2014 Boe Mcf bbl | Jun. 30, 2013 Boe Mcf bbl
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Balance at the beginning of the period (in BOE) | Boe | 12,446,394 |  | 13,289,510 |  | 13,766,440 |  |
Revisions of previous estimates (in BOE) | Boe | (964,171) | [1] | (390,330) | [2] | (247,350) | [3] |
Improved recovery, extensions and discoveries (in BOE) | Boe | 0 |  | 0 |  | 132,884 |  |
Sales of minerals in place (in BOE) | Boe | 0 |  | 0 |  | (184,722) |  |
Production (sales volumes) (in BOE) | Boe | (658,802) |  | (452,786) |  | (177,742) |  |
Balance at the end of the period (in BOE) | Boe | 10,823,421 |  | 12,446,394 |  | 13,289,510 |  |
Proved developed reserves (in BOE) | Boe | 7,168,249 |  | 7,349,626 |  | 7,970,562 |  | 10,089,861
Proved undeveloped reserves (in BOE) | Boe | 3,655,172 |  | 5,096,768 |  | 5,318,948 |  | 3,676,579
Delhi Field |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Revisions of previous estimates (in BOE) | Boe |  |  |  |  | 1,679,481 |  |
Crude Oil |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Balance at the beginning of the period (in Bbls/Mcf) | 10,011,976 |  | 10,526,344 |  | 12,782,755 |  |
Revisions of previous estimates (in Bbls/Mcf) | (765,385) | [1] | (64,074) | [2] | (1,919,052) | [3] |
Improved recovery, extensions and discoveries (in Bbls/Mcf) | 0 |  | 0 |  | 17,146 |  |
Sales of minerals in place (in Bbls/Mcf) | 0 |  | 0 |  | (184,722) |  |
Production (sales volumes) (in Bbls/Mcf) | (658,041) |  | (450,294) |  | (169,783) |  |
Balance at the end of the period (in Bbls/Mcf) | 8,588,550 |  | 10,011,976 |  | 10,526,344 |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Proved developed reserves (in Bbls/Mcf) | 7,168,249 |  | 7,347,231 |  | 7,858,224 |  | 10,077,522
Proved undeveloped reserves (in Bbls/Mcf) | 1,420,301 |  | 2,664,745 |  | 2,668,120 |  | 2,705,233
Crude Oil | Delhi Field |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Revisions of previous estimates (in Bbls/Mcf) |  |  |  |  | 1,817,224 |  |
Natural Gas Liquids |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Balance at the beginning of the period (in Bbls/Mcf) | 2,433,595 |  | 2,278,688 |  | 979,885 |  |
Revisions of previous estimates (in Bbls/Mcf) | (198,233) | [1] | 156,195 | [2] | 1,269,588 | [3] |
Improved recovery, extensions and discoveries (in Bbls/Mcf) | 0 |  | 0 |  | 32,731 |  |
Sales of minerals in place (in Bbls/Mcf) | 0 |  | 0 |  | 0 |  |
Production (sales volumes) (in Bbls/Mcf) | (491) |  | (1,288) |  | (3,516) |  |
Balance at the end of the period (in Bbls/Mcf) | 2,234,871 |  | 2,433,595 |  | 2,278,688 |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Proved developed reserves (in Bbls/Mcf) | 0 |  | 1,572 |  | 32,164 |  | 8,539
Proved undeveloped reserves (in Bbls/Mcf) | 2,234,871 |  | 2,432,023 |  | 2,246,524 |  | 971,346
Natural Gas Liquids | Giddings Field |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Revisions of previous estimates (in Bbls/Mcf) |  |  | (29,304) |  |  |  |
Natural Gas |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Balance at the beginning of the period (in Bbls/Mcf) | Mcf | 4,939 |  | 2,906,863 |  | 22,797 |  |
Revisions of previous estimates (in Bbls/Mcf) | Mcf | (3,319) | [1] | (2,894,703) | [2] | 2,412,677 | [3] |
Improved recovery, extensions and discoveries (in Bbls/Mcf) | Mcf | 0 |  | 0 |  | 498,044 |  |
Sales of minerals in place (in Bbls/Mcf) | Mcf | 0 |  | 0 |  | 0 |  |
Production (sales volumes) (in Bbls/Mcf) | Mcf | (1,620) |  | (7,221) |  | (26,655) |  |
Balance at the end of the period (in Bbls/Mcf) | Mcf | 0 |  | 4,939 |  | 2,906,863 |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Proved developed reserves (in Bbls/Mcf) | Mcf | 0 |  | 4,939 |  | 481,042 |  | 22,797
Proved undeveloped reserves (in Bbls/Mcf) | Mcf | 0 |  | 0 |  | 2,425,821 |  | 0
Natural Gas | Delhi Field |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Revisions of previous estimates (in Bbls/Mcf) | Mcf |  |  | (2,246,524) |  |  |  |
Natural Gas | Giddings Field |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |
Revisions of previous estimates (in Bbls/Mcf) | Mcf |  |  | (452,786) |  |  |  |
[1] | The negative revision results primarily from the removal of proved undeveloped reserves in the far eastern part of the Delhi field, referred to as Test Site 6, which were deemed uneconomic under the lower SEC price case utilized at the end of the period.
[2] | The 2,894,703 negative fiscal 2015 revision for natural gas primarily reflects a 2,246,524 MCF negative revision for the Delhi field NGL plant together with a 452,786 MCF negative revision at the Giddings Field for a well that was lost due to mechanical issues. The NGL plant revision resulted from a decision during the current fiscal year to use the methane production internally to reduce field operating costs rather than selling it into the market. The 156,195 BBL positive natural gas liquids revision primarily reflects 185,499 BBL positive revision for better recovery from the redesigned NGL plant, partly offset by a 29,304 BBL negative revision due to the lost Giddings well.
[3] | Significant reserve revisions occurred in the Delhi field during fiscal 2014. As a result of a fluid release event in the field, 1,817,224 BBLs of oil reserves were reclassified from proved to probable category based on the operator's decision to defer CO2 injections in certain parts of the field. There was a positive revision of 1,679,481 BOE, which was comprised of 1,275,178 BBLs of natural gas liquids and 2,425,821 MCF of natural gas as a result of an improved design for the NGL plant in the Delhi field. The plant was expected to significantly increase recoveries of these products, particularly natural gas, which were not previously planned to be extracted from the injection volumes.

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- Definition Additions to proved reserves, measured in energy equivalents, that result from (1) improved recovery (2) extension of the proved acreage of previously discovered (old) reservoirs through additional drilling in periods after discovery and (3) discovery of new fields with proved reserves or of new reservoirs of proved reserves in old fields. + References No definition available. + Details
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- Definition 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). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10.(a)(2)) -URI http://asc.fasb.org/extlink&oid=50486907&loc=d3e511914-122862 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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- Definition 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). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
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