Income Taxes (Reconciliation of Income Tax Rate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Provision at the U.S. statutory rate of 21%	$ 93.5	$ 106.7	$ 98.3
Increase (reduction) in tax expense resulting from:
State income tax, net of federal income tax benefit	10.8	13.2	15.5
Tax credits, net of unrecognized tax benefits	(7.8)	(13.8)	(2.5)
Change in unrecognized tax benefits	0.2	3.1	0.4
Change in valuation allowance	7.8	1.9	5.0
Foreign taxes at rates other than U.S. statutory rate	(33.6)	(20.7)	(3.2)
Deemed inclusions	9.2	8.3	3.9
global intangible low taxed income	10.3	9.5	0.7
Change in rates from the Tax Act & other law changes	0.7	(0.8)	1.9
Excess tax benefits from stock-based compensation	(4.2)	(10.9)	(10.5)
Miscellaneous other	1.2	2.6	(1.9)
Total provision for income taxes	$ 88.1	$ 99.1	$ 107.6