Supplementary Information On Oil, NGL And Natural Gas Reserves (Summary of Proved Developed and Undeveloped Reserves) (Details)	Sep. 30, 2017 bbl Mcf	Sep. 30, 2016 bbl Mcf	Sep. 30, 2015 bbl Mcf
Oil [Member]
Reserve Quantities [Line Items]
Proved Developed Reserves (Volume)	2,201,528	1,980,519	2,725,077
Proved Undeveloped Reserves (Volume)	3,308,139	3,445,571	4,313,353
Natural Gas Liquids [Member]
Reserve Quantities [Line Items]
Proved Developed Reserves (Volume)	1,768,425	1,095,256	1,466,834
Proved Undeveloped Reserves (Volume)	616,274	527,447	1,453,766
Natural Gas [Member]
Reserve Quantities [Line Items]
Proved Developed Reserves (Volume) | Mcf	87,861,043	62,929,047	82,899,159
Proved Undeveloped Reserves (Volume) | Mcf	33,334,077	18,796,551	37,314,885