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	Dec. 31, 2013
Income Taxes [Abstract]
Effective income tax rate (in hundredths)	35.50%	39.70%	37.90%	41.20%
U.S. Federal statutory rate (in hundredths)	35.00%		35.00%
Expected annual effective income tax rate			approximately 37%
Gross unrecognized tax benefits, including interest and penalties	$ 33.8		$ 33.8		$ 32.3
Related tax benefits	(1.9)		(1.9)		(1.9)
Net unrecognized tax benefits	$ 31.9		$ 31.9		$ 30.4