Summary of Significant Accounting Policies, Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Income tax
Undistributed foreign earnings				$ 900.0
Provisional Tax Act Charge			$ 398.5
Income tax expense (benefit)	$ (14.5)	$ (14.5)