Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Taxes
Income tax provisions	$ 18.7		$ 18.0	$ 57.2	$ 58.5
Effective tax rate (as a percent)	27.90%		31.10%	29.00%	31.60%
Tax benefit from favorable tax return to provision adjustments and release of reserves for uncertain tax positions	1.8
Retroactive benefit from 2012 Research & Development tax credits		$ 0.6