Other Comprehensive Income Other Comprehensive Income Phantom (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Tax Expense (Benefit)	$ 25.6	$ 38.9	$ 68.4
Reclassification out of Accumulated Other Comprehensive Income | Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss) before reclassifications, Tax	0.0	0.0
Income Tax Expense (Benefit)	0.0	0.0
Reclassification from AOCI, Current Period, Tax	0.0	0.0
Reclassification out of Accumulated Other Comprehensive Income | Defined Benefit Pension and Postretirement Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss) before reclassifications, Tax	0.1	0.0
Income Tax Expense (Benefit)	0.0	0.0
Reclassification from AOCI, Current Period, Tax	$ 0.0	$ 0.0