Retirement Plan And Other Post-Retirement Benefits (Schedule Of Expected Benefit Payments) (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
2018 - Benefit Payments	$ 64,400
2019 - Benefit Payments	65,000
2020 - Benefit Payments	65,400
2021 - Benefit Payments	65,800
2022 - Benefit Payments	66,200
2023 through 2027 - Benefit Payments	331,100
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
2018 - Benefit Payments	26,483
2018 - Subsidy Receipts	(1,910)
2019 - Benefit Payments	27,456
2019 - Subsidy Receipts	(2,074)
2020 - Benefit Payments	28,359
2020 - Subsidy Receipts	(2,225)
2021 - Benefit Payments	29,173
2021 - Subsidy Receipts	(2,369)
2022 - Benefit Payments	29,757
2022 - Subsidy Receipts	(2,515)
2023 through 2027 - Benefit Payments	152,957
2023 through 2027 - Subsidy Receipts	$ (14,271)