Income Taxes - Additional Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 21.2	$ 18.7		$ 66.9	$ 57.2
Effective tax rate (as a percent)	27.70%			30.80%
Benefit from favorable tax return to provision adjustments and release of reserves for uncertain tax positions	$ 1.7	$ 1.8	$ 0.6