Income Taxes (Components Of Federal And State Income Taxes Included In The Consolidated Statements Of Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Income Taxes [Abstract]
Current Income Taxes - Federal			$ (4)	$ 0
Current Income Taxes - State			3,906	3,677
Deferred Income Taxes - Federal			66,416	87,598
Deferred Income Taxes - State			15,280	18,912
Income Tax Expense	44,873	72,136	85,598	110,187
Deferred Investment Tax Credit			(291)	(348)
Total Income Taxes			85,307	109,839
Other Income			(291)	(348)
Income Tax Expense	$ 44,873	$ 72,136	$ 85,598	$ 110,187