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Pension And Other Postretirement Benefits (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 2.1
Defined Benefit Plan, Pension Asset, (Increase)Decrease For Remeasurement Due To Settlement	(6.1)
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement	(0.2)
Change in Regulatory Assets Due to Interim Measurement	1.4
Change in Accumulated Other Comprehensive Income Due to Interim Measurement	0.2
Change to Defined Benefit Plan Net Periodic Costs Due to Interim Measurement	(1.4)
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 16.7

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Amount of (increase) decrease to benefit obligation of defined benefit plan from remeasurement due to settlement. Excludes decrease to benefit obligation for settlement payment.

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