Other Operating Credits and Charges, Net Non-Operating Income and Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Income and Expenses [Abstract]
Interest Expense	$ (18.0)	$ (19.0)	$ (20.0)
Interest expense, net of capitalized interest	(19.0)	(16.0)	(19.0)
Investment Income, Interest and Dividend	9.0	18.0	10.0
Gain on securities	0.0	1.0	0.0
Interest Income, Other	1.0	(1.0)	1.0
Investment income	10.0	18.0	11.0
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	(3.0)	(4.0)	(10.0)
Foreign Currency Transaction Gain (Loss), Realized	(5.0)	0.0	(4.0)
Gain on Acquisition	14.0	0.0	0.0
Other nonoperating items	6.0	(4.0)	(14.0)
Nonoperating Income (Expense)	(3.0)	(2.0)	(23.0)
Amortization of financing costs and discounts	2.0	1.0	1.0
Interest Costs Capitalized Adjustment	$ 1.0	$ 4.0	$ 2.0