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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, 2015 Boe Mcf bbl | Jun. 30, 2014 Boe Mcf bbl | Jun. 30, 2013 Boe Mcf bbl | Jun. 30, 2012 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 |  | 13,289,510 |  | 13,766,440 |  | 13,441,116 |  |
Revisions of previous estimates (in BOE) | Boe |  | (390,330) | [1] | (247,350) | [2] | 2,806,181 | [3] |
Improved recovery, extensions and discoveries (in BOE) | Boe |  | 0 |  | 132,884 |  |  |  |
Sales of minerals in place (in BOE) | Boe |  | 0 |  | (184,722) |  | (2,254,038) |  |
Production (sales volumes) (in BOE) | Boe |  | (452,786) |  | (177,742) |  | (226,819) |  |
Balance at the end of the period (in BOE) | Boe |  | 12,446,394 |  | 13,289,510 |  | 13,766,440 |  |
Proved developed reserves (in BOE) | Boe |  | 7,349,626 |  | 7,970,562 |  | 10,089,861 |  | 8,032,809
Proved undeveloped reserves (in BOE) | Boe |  | 5,096,768 |  | 5,318,948 |  | 3,676,579 |  | 5,408,307
Delhi Field |  |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |  |
Positive revision of previous estimate (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) |  | 10,526,344 |  | 12,782,755 |  | 11,638,618 |  |
Revisions of previous estimates (in Bbls/Mcf) |  | (64,074) | [1] | (1,919,052) | [2] | 1,826,053 | [3] |
Improved recovery, extensions and discoveries (in Bbls/Mcf) |  | 0 |  | 17,146 |  |  |  |
Sales of minerals in place (in Bbls/Mcf) |  | 0 |  | (184,722) |  | (485,536) |  |
Production (sales volumes) (in Bbls/Mcf) |  | (450,294) |  | (169,783) |  | (196,380) |  |
Balance at the end of the period (in Bbls/Mcf) |  | 10,011,976 |  | 10,526,344 |  | 12,782,755 |  |
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) |  | 7,347,231 |  | 7,858,224 |  | 10,077,522 |  | 7,670,934
Proved undeveloped reserves (in Bbls/Mcf) |  | 2,664,745 |  | 2,668,120 |  | 2,705,233 |  | 3,967,684
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) |  | 2,278,688 |  | 979,885 |  | 492,473 |  |
Revisions of previous estimates (in Bbls/Mcf) |  | 156,195 | [1] | 1,269,588 | [2] | 975,515 | [3] |
Improved recovery, extensions and discoveries (in Bbls/Mcf) |  | 0 |  | 32,731 |  |  |  |
Sales of minerals in place (in Bbls/Mcf) |  | 0 |  | 0 |  | (480,832) |  |
Production (sales volumes) (in Bbls/Mcf) |  | (1,288) |  | (3,516) |  | (7,271) |  |
Balance at the end of the period (in Bbls/Mcf) |  | 2,433,595 |  | 2,278,688 |  | 979,885 |  |
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) |  | 1,572 |  | 32,164 |  | 8,539 |  | 111,978
Proved undeveloped reserves (in Bbls/Mcf) |  | 2,432,023 |  | 2,246,524 |  | 971,346 |  | 380,495
Revision due to improved design (in Bbls/Mcf) | [1] | 185,499 |  |  |  |  |  |
Natural Gas Liquids | Delhi Field |  |  |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |  |
Revision due to improved design (in Bbls/Mcf) |  |  |  | 1,275,178 |  |  |  |
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) | [1] | (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 |  | 2,906,863 |  | 22,797 |  | 7,860,156 |  |
Revisions of previous estimates (in Bbls/Mcf) | Mcf |  | (2,894,703) | [1] | 2,412,677 | [2] | 27,679 | [3] |
Improved recovery, extensions and discoveries (in Bbls/Mcf) | Mcf |  | 0 |  | 498,044 |  |  |  |
Sales of minerals in place (in Bbls/Mcf) | Mcf |  | 0 |  | 0 |  | (7,726,032) |  |
Production (sales volumes) (in Bbls/Mcf) | Mcf |  | (7,221) |  | (26,655) |  | (139,006) |  |
Balance at the end of the period (in Bbls/Mcf) | Mcf |  | 4,939 |  | 2,906,863 |  | 22,797 |  |
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 |  | 4,939 |  | 481,042 |  | 22,797 |  | 1,499,382
Proved undeveloped reserves (in Bbls/Mcf) | Mcf |  | 0 |  | 2,425,821 |  | 0 |  | 6,360,774
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 | [1] | (2,246,524) |  |  |  |  |  |
Estimated quantities of proved oil and natural gas reserves and changes in quantities of proved developed and undeveloped reserves |  |  |  |  |  |  |  |
Revision due to improved design (in Bbls/Mcf) | Mcf |  |  |  | 2,425,821 |  |  |  |
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 | [1] | (452,786) |  |  |  |  |  |
[1] | The 2,894,703 negative fiscal 2015 revision for natural gas primarily reflects a 2,246,524 MCF negative revision for the Delhi Field gas plant together with a 452,786 MCF negative revision at the Giddings Field for a well that was lost due to excessive formation solids that kept interfering with pumping. The gas 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 gas plant, partly offset by a 29,304 BBL negative revision due to the lost Giddings well.
[2] | Significant reserve revisions occurred in the Delhi Field during fiscal 2014. As a result of an adverse 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 gas plant in the Delhi Field. The plant is expected to significantly increase recoveries of these products, particularly natural gas, which was not previously planned to be extracted from the injection volumes.
[3] | A significant upward reserve revision occurred in the Delhi Field during fiscal 2013 as a result of (1) revised geological maps based on production results and acquired seismic data, (2) inclusion of an additional reservoir with similar features, production history and suitability for EOR, and (3) inclusion of natural gas processing at Delhi.

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