Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Effective income tax rate (as a percent)	30.60%	37.50%	33.60%	32.90%
Federal statutory income tax rate			35.00%	35.00%
Gain on share repurchase			$ 18.1	$ 0
Income tax benefit			$ (2.5)	$ (16.1)