Income Tax (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating Loss Carryforwards [Line Items]
Effective tax rate (as a percent)	182.00%	(2.00%)	12.00%	9.00%
Federal statutory income tax rate (percent)			35.00%
Net discrete tax benefit	$ 14.3	$ 8.2
Reduction in unrecognized tax benefits primarily resulting from expiration of statutes of limitations	$ 8.1