Supplementary Information on Oil, Ngl and Natural Gas Reserves (Unaudited) (Details 3)	Sep. 30, 2012 bbl	Sep. 30, 2011 bbl	Sep. 30, 2010 bbl
Reserve Quantities [Line Items]
Proved Undeveloped Reserves	50,885,055	44,575,844
Oil (Barrels) [Member]
Reserve Quantities [Line Items]
Proved Developed Reserves (Volume)	849,548	759,989	861,240
Proved Undeveloped Reserves (Volume)	222,771	83,749	63,769
Natural Gas (Mcf) [Member]
Reserve Quantities [Line Items]
Proved Developed Reserves (Volume)	65,733,119	60,193,878	57,344,190
Proved Undeveloped Reserves (Volume)	47,780,937	41,644,106	40,826,265
NGL (Barrels) [Member]
Reserve Quantities [Line Items]
Proved Developed Reserves (Volume)	494,160	386,774
Proved Undeveloped Reserves (Volume)	294,582	404,874

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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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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