Basic and Diluted Net Loss Per Share - Schedule of the Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Loss (numerator):
Net loss	$ (51.7)	$ (102.2)	$ (144.0)	$ (188.6)
Shares (denominator):
Basic weighted-average common shares outstanding (in shares)	87,300,000.00	85,900,000	86,900,000	85,600,000
Diluted weighted-average common shares outstanding (in shares)	87,300,000.00	85,900,000	86,900,000	85,600,000
Basic and diluted net loss per share:
Basic net loss per share (in USD per share)	$ (0.59)	$ (1.19)	$ (1.66)	$ (2.20)
Diluted net loss per share (in USD per share)	$ (0.59)	$ (1.19)	$ (1.66)	$ (2.20)