Income Taxes, Provision and Effective tax rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Taxes
Provision for income taxes	$ (78.1)	$ (68.0)	$ (182.2)	$ (114.0)
Effective tax rate	17.50%	20.70%	20.60%	18.50%
Discrete income tax benefit, tax on foreign income				$ 19.9
Discrete income tax benefit, impact on effective tax rate				(3.20%)
Tax settlement, amount	$ (14.9)		$ (14.9)
Tax settlement, effective tax rate	(3.30%)		(1.70%)
Excess tax benefit from option exercises	$ 19.3	$ 12.4	$ 22.0	$ 17.4
Excess tax benefit, impact on effective tax rate	(4.30%)	(3.80%)	(2.50%)	(2.80%)
Impact of acquisition-related expenses on the effective tax rate	0.60%		0.30%