Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2.7	$ 1.8	$ 28.1	$ 5.6
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0.3	$ 0.5	1.6	$ 1.3
2015			0.3
2016			1.1
2017			0.5
2018			0.3
2019			0.1
Restricted Stock Units and Performance-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
2015			3.1
2016			5.0
2017			2.1
2018			1.2
2019			0.3
2020 & thereafter			$ 1.5