Reportable Business Segments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 260.2us-gaap_OperatingIncomeLoss	$ 232.1us-gaap_OperatingIncomeLoss
Interest expense	(17.0)us-gaap_InterestExpense	(19.1)us-gaap_InterestExpense
Stock-based compensation expense	(10.1)	(9.3)
Acquisition-related expenses		(2.0)
Income before income taxes	247.3	217.1
Operating Segment
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	281.2	253.4
Unallocated amount to segment
Reconciliation of segment operating income to consolidated income before income taxes
Interest expense	(17.0)	(19.1)
Interest Income	4.5	4.4
Stock-based compensation expense	(10.1)	(9.3)
Acquisition-related expenses		(2.0)
Other costs, net	(11.3)	(10.3)
Income before income taxes	$ 247.3	$ 217.1

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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