Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
Repatriation of foreign cash			$ 93.0
Income taxes	$ 65.3	$ 57.3		$ 169.2		$ 157.6
Cash and cash equivalents	210.6	$ 370.2		210.6		370.2	$ 423.0	$ 496.9
Deferred tax benefit				(8.7)	[1]	$ 0.1
Foreign Cash Repatriated
Income Tax [Line Items]
Income taxes			2.7
Deferred tax benefit			$ 11.6
Outside U.S.
Income Tax [Line Items]
Cash and cash equivalents	$ 142.2			$ 142.2

[1] See Note 18 for a discussion of the tax impact of foreign cash repatriation.