Reportable Business Segments, Reconciliation of Segment Operating Income to Consolidated Income Before Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information
Segment operating income	$ 376.2	$ 376.9
Interest expense	(29.7)	(24.5)
Other income, net	3.0	2.3
Stock-based compensation expense	(14.4)	(12.7)
Acquisition-related expenses	(16.5)
Other operating expenses	(13.4)	(12.8)
Income before income taxes	349.5	354.7
Operating Segment
Segment Reporting Information
Segment operating income	$ 420.5	$ 402.4

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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