Income Taxes - Income Tax Expense by Component (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 166.5	$ 224.7	$ 192.6
State	49.2	56.1	43.3
Foreign	18.3	20.0	17.7
Total current	234.0	300.8	253.6
Deferred:
Domestic	(18.8)	(83.0)	(52.7)
Foreign	(1.4)	(4.9)	(3.4)
Total deferred	(20.2)	(87.9)	(56.1)
Income tax expense	$ 213.8	$ 212.9	$ 197.5