Income Taxes (Components Of Federal And State Income Taxes Included In The Consolidated Statements Of Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Current Income Taxes [Abstract]
Federal	$ 32,034	$ (6,658)	$ 25,064
State	10,673	20,903	13,387
Deferred Income Taxes [Abstract]
Federal	103,046	(164,818)	(244,336)
State	14,929	(81,976)	(113,251)
Income Tax Expense (Benefit)	160,682	(232,549)	(319,136)
Deferred Investment Tax Credit	(173)	(348)	(414)
Total Income Taxes	160,509	(232,897)	(319,550)
Presented as Follows [Abstract]
Other Income	(173)	(348)	(414)
Income Tax Expense (Benefit)	$ 160,682	$ (232,549)	$ (319,136)