Income Taxes - Income Tax Provision (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Federal	$ 17.2	$ 211.7	$ 35.6
State	10.8	8.4	4.0
Non-United States	181.9	168.6	144.0
Total current	209.9	388.7	183.6
Deferred
Federal	(7.5)	(178.2)	69.7
State	1.0	(0.8)	0.5
Non-United States	(5.4)	(17.8)	3.8
Total deferred	(11.9)	(196.8)	74.0
Total provision	$ 198.0	$ 191.9	$ 257.6