Income Taxes (Significant Components Of Deferred Tax Liabilities And Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Deferred Tax Liabilities [Abstract]
Property, Plant and Equipment	$ 1,141,432	$ 1,049,100
Pension and Other Post-Retirement Benefit Costs	79,516	151,903
Unrealized Hedging Gains	19,127	50,179
Other	57,919	55,457
Total Deferred Tax Liabilities	1,297,994	1,306,639
Deferred Tax Assets [Abstract]
Pension and Other Post-Retirement Benefit Costs	(123,532)	(195,829)
Tax Loss and Credit Carryforwards	(200,344)	(194,875)
Other	(82,831)	(92,140)
Total Deferred Tax Assets	(406,707)	(482,844)
Total Net Deferred Income Taxes	$ 891,287	$ 823,795