Supplementary Information On Oil, Ngl And Natural Gas Reserves (Summary of Net Quantities of Proved, Developed and Undeveloped Oil and Natural Gas Reserves) (Details)	12 Months Ended
	Sep. 30, 2014 bbl	Sep. 30, 2013 bbl	Sep. 30, 2012 bbl
Oil [Member]
Reserve Quantities [Line Items]
Proved Oil and Natural Gas Reserves, Beginning Balance	1,643,303	1,072,319	843,738
Revisions of previous estimates	(50,025)	(90,968)	8,627
Acquisitions (divestitures)	5,882,886
Extensions and discoveries and other additions	439,802	896,036	373,097
Production	(346,387)	(234,084)	(153,143)
Proved Oil and Natural Gas Reserves, Ending Balance	7,569,579	1,643,303	1,072,319
Natural Gas Liquids [Member]
Reserve Quantities [Line Items]
Proved Oil and Natural Gas Reserves, Beginning Balance	1,616,126	788,742	791,648
Revisions of previous estimates	469,897	141,081	(76,794)
Acquisitions (divestitures)	884,889
Extensions and discoveries and other additions	276,957	798,200	172,602
Production	(207,688)	(111,897)	(98,714)
Proved Oil and Natural Gas Reserves, Ending Balance	3,040,181	1,616,126	788,742
Natural Gas [Member]
Reserve Quantities [Line Items]
Proved Oil and Natural Gas Reserves, Beginning Balance	132,289,167	113,514,056	101,837,984
Revisions of previous estimates	(3,917,380)	(2,697,853)	(27,389,752)
Acquisitions (divestitures)	8,191,448	1,660,649	19,075,529
Extensions and discoveries and other additions	16,702,684	30,698,644	29,062,593
Production	(10,773,559)	(10,886,329)	(9,072,298)
Proved Oil and Natural Gas Reserves, Ending Balance	142,492,360	132,289,167	113,514,056