New Accounting Standards (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Defined Benefit Plan, Service Cost	$ 2.5	$ 2.4	$ 7.8	$ 8.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	1.4	2.8	5.3	8.4
Tax expense (benefit)	14.0	$ 14.4	19.1	$ 38.3
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess tax benefit from share-based compensation, Operating activities			30.3
Tax expense (benefit)	(4.8)		(30.3)
Accounting Standards Update 2017-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Defined Benefit Plan, Service Cost	2.5		7.8
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating leases, Future minimum payments due	77.6		77.6
Accounting Standards Update 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New accounting pronouncement cumulative effect of change on equity	$ (4.1)		$ (4.1)