Income Taxes, Provision and Effective tax rate (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Taxes
Provision for income taxes	$ (104.1)	$ (46.0)
Effective tax rate	23.90%	15.90%
Discrete income tax benefit, tax on foreign income		$ 19.9
Discrete income tax benefit, impact on effective tax rate		(6.90%)
Excess tax benefit from option exercises	$ 2.6	$ 5.0
Excess tax benefit, impact on effective tax rate	(0.60%)	(1.70%)