Pension and Postretirement Health and Life Benefits (Schedule of Net Benefit Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Actuarial (Gain) Loss From Remeasurement	$ (17.3)	$ 25.8
Pension Plan, Defined Benefit [Member]
Service costs	3.4	3.7
Interest costs	28.7	32.2
Expected return on plan assets (gains)	(41.0)	(40.7)
Actuarial (gains) losses, net	30.4	(10.9)
Defined Benefit Plan, Actuarial (Gain) Loss From Remeasurement	(50.8)	32.8
Net periodic benefit cost (credit)	21.5	(15.7)
Postretirement Health and Life Benefits Plans [Member]
Interest costs	5.8	7.2
Amortization of prior service costs (credits), net	(0.2)	(0.1)
Actuarial (gains) losses, net	(13.1)	(24.9)
Defined Benefit Plan, Actuarial (Gain) Loss From Remeasurement	(13.1)	(24.8)
Loss on plan changes resulting from legal settlement		10.0
Net periodic benefit cost (credit)	$ (7.5)	$ (7.8)