Reportable Business Segments, Reconciliation of Segment Operating Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 376.9	$ 314.1
Interest expense	(24.5)	(19.3)
Other income, net	2.3	3.6
Stock-based compensation expense	(12.7)	(12.1)
Other operating expenses	(12.8)	(11.4)
Income before income taxes	354.7	298.4
Operating Segment
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 402.4	$ 337.6