Supplementary Information For Oil And Gas Producing Activities (Costs Incurred In Oil And Gas Property Acquisition, Exploration And Development Activities) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Supplementary Information For Oil And Gas Producing Activities Unaudited [Abstract]
Proved		$ 1,342	$ 1,767	$ 18,213
Unproved		2,165	19,998	7,884
Exploration Costs	[1]	27,561	53,222	71,850
Development Costs	[2]	219,386	454,605	490,164
Asset Retirement Costs		(49,653)	37,595	(4,946)
Total Property Acquisition Costs		200,801	567,187	583,165
Capitalized interest included in exploration costs		300	400	700
Capitalized interest included in development costs		$ 200	$ 500	$ 700

[1] Amounts for 2016, 2015 and 2014 include capitalized interest of $0.3 million, $0.4 million and $0.7 million, respectively.

[2] Amounts for 2016, 2015 and 2014 include capitalized interest of $0.2 million, $0.5 million and $0.7 million, respectively.