Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income before income taxes:
United States	$ 360.8	$ 354.7	$ 349.5
International	106.2	88.4	80.9
Income before income taxes	467.0	443.1	430.4
Provision for income taxes — current:
Federal	12.3	164.1	85.5
State	21.8	15.3	17.4
International	17.8	28.1	17.0
Total provision — current	51.9	207.5	119.9
Provision for income taxes — deferred:
Federal	35.0	(10.4)	13.5
State	9.4	(0.9)	1.3
International	4.6	(3.0)	(2.1)
Total provision — deferred	49.0	(14.3)	12.7
TOTAL PROVISION FOR INCOME TAXES	$ 100.9	$ 193.2	$ 132.6