Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended			6 Months Ended			12 Months Ended				6 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Mar. 31, 2014		Mar. 31, 2013	Sep. 30, 2013		Mar. 31, 2014 Reserve For Gas Replacement [Member]	Sep. 30, 2013 Reserve For Gas Replacement [Member]	Mar. 31, 2014 Stock Options [Member]	Mar. 31, 2014 Restricted Shares [Member]	Mar. 31, 2014 Stock Appreciation Right [Member]	Mar. 31, 2014 Non-performance Based Restricted Stock Units [Member]	Mar. 31, 2014 Performance Shares [Member]	Mar. 31, 2014 Exchange Traded Futures Contracts [Member]	Sep. 30, 2013 Exchange Traded Futures Contracts [Member]	Sep. 30, 2014 Subsequent Event [Member] Reserve For Gas Replacement [Member]
Summary Of Significant Accounting Policies [Line Items]
Hedging collateral deposits	$ 0	[1]		$ 0	[1]		$ 1,094,000	[1]								$ 0	$ 1,100,000
Gas stored underground - current	(3,176,000)			(3,176,000)			(51,484,000)		73,883,000	0								0
Capitalized costs of unproved properties excluded from amortization				184,500,000			106,100,000
Full cost ceiling test discount factor	10.00%			10.00%
Amount full cost ceiling exceeds book value of oil and gas properties	$ 204,000,000			$ 204,000,000
Antidilutive securities	0		208,819	265		362,681
Share based compensation other than options grants in period												0	0	80,951	116,090
Granted in fiscal year, weighted average grant date fair value														$ 65.23	$ 67.16
Stock options granted											0

[1] Netting Adjustments represent the impact of legally-enforceable master netting arrangements that allow the Company to net gain and loss positions held with the same counterparties. The net asset or net liability for each counterparty is recorded as an asset or liability on the Company’s balance sheet.