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, 2020	Sep. 30, 2019	Sep. 30, 2018
Supplementary Information For Oil And Gas Producing Activities Unaudited [Abstract]
Proved		$ 245,976	$ 3,136	$ 1,544
Unproved		42,922	3,679	4,286
Exploration Costs		3,891	2,060	29,365
Development Costs	[1]	355,742	468,498	332,496
Asset Retirement Costs		62,080	26,192
Asset Retirement Costs				(10,107)
Total Property Acquisition Costs		710,611	503,565	357,584
Capitalized interest included in development costs		$ 1,000	$ 200	$ 300

[1] Amounts for 2020, 2019 and 2018 include capitalized interest of $1.0 million, $0.2 million and $0.3 million, respectively.