Income Taxes (Components Of Federal And State Income Taxes Included In The Consolidated Statements Of Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Current Income Taxes [Abstract]
Federal			$ 34,113	$ 7,995
State			11,509	15,537
Deferred Income Taxes [Abstract]
Federal			51,749	(197,982)
State			12,032	(85,930)
Income Tax Expense (Benefit)	$ 52,971	$ (116,030)	109,403	(260,380)
Deferred Investment Tax Credit			(86)	(174)
Total Income Taxes			109,317	(260,554)
Presented as Follows [Abstract]
Other Income			(86)	(174)
Income Tax Expense (Benefit)	$ 52,971	$ (116,030)	$ 109,403	$ (260,380)