Employee Benefit Plans and Other Postretirement Benefits (Schedule Of Expected Benefit Payments For Next Five Years And Thereafter) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Pension Plan Assets
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Expected benefit payments in 2018	$ 90,510
Expected benefit payments in 2019	92,694
Expected benefit payments in 2020	95,930
Expected benefit payments in 2021	98,109
Expected benefit payments in 2022	102,258
Expected benefit payments Thereafter	574,745
SERPA Benefits
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Expected benefit payments in 2018	3,346
Expected benefit payments in 2019	2,325
Expected benefit payments in 2020	2,843
Expected benefit payments in 2021	3,294
Expected benefit payments in 2022	3,528
Expected benefit payments Thereafter	27,719
Postretirement Health Coverage
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Expected benefit payments in 2018	28,446
Expected benefit payments in 2019	28,309
Expected benefit payments in 2020	27,351
Expected benefit payments in 2021	26,175
Expected benefit payments in 2022	25,096
Expected benefit payments Thereafter	$ 120,438