Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Net unrecognized tax benefit	$ 67.6		$ 66.9
Income tax interest and penalties accrued	0.8
Deferred tax assets	$ 120.5
Effective tax rate	18.90%	18.60%
U.S. federal statutory rate	35.00%