Earnings Loss Per Share - Computation of Weighted Average Shares Outstanding (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Earnings Per Share [Line Items]
Net loss attributable to common stockholders	$ (1.9)	$ 104.7	$ (8.8)	$ (134.8)	$ (129.6)	$ (140.1)	$ (12.2)	$ (26.7)	$ (266.7)	$ 11.9	$ (0.4)	$ (7.4)	$ (40.8)	$ (308.6)	$ (262.6)
Adjustments to the numerator for diluted earnings per share:
Gain on settlement agreement related to Series B Convertible Preferred Stock													(103.0)	0.0	0.0
Gain on amendment of Series B Convertible Preferred Stock													(32.9)	0.0	0.0
Remeasurement adjustment associated with the Preferred Series B redemption liability													5.0	0.0	0.0
Loss attributed to PDH non-controlling interest													(5.9)	0.0	0.0
Net loss attributable to common stockholders for diluted EPS													$ (177.6)	$ (308.6)	$ (262.6)
Basic weighted average common stock outstanding (in shares)													243,300,000	203,200,000	135,300,000
Share adjustments (in shares)													29,000,000	0	0
Dilutive weighted average common stock outstanding (in shares)													272,300,000	203,200,000	135,300,000
Loss per share attributable to common stockholders:
Basic (in dollars per share)	$ (0.01)	$ 0.45	$ (0.04)	$ (0.59)	$ (0.60)	$ (0.66)	$ (0.06)	$ (0.14)	$ (1.59)	$ 0.09	$ 0.00	$ (0.07)	$ (0.17)	$ (1.52)	$ (1.94)
Diluted (in dollars per share)	$ (0.01)	$ (0.15)	$ (0.04)	$ (0.59)	$ (0.60)	$ (0.66)	$ (0.06)	$ (0.14)	$ (1.59)	$ 0.08	$ 0.00	$ (0.07)	(0.65)	(1.52)	(1.94)
Dividends per share paid to common stockholders (in dollars per share)													$ 0	$ 0	$ 0
Series B Preferred Stock
Adjustments to the numerator for diluted earnings per share:
Conversion related to the amendment of Series B Preferred Stock - assumed at beginning of reporting period (in shares)													15,300,000	0	0
Settlement of preferred stock redemption liability - assumed at beginning of reporting period (in shares)													5,700,000	0	0
Loss per share attributable to common stockholders:
Incremental Common Shares Attributable To Dilutive Effect of Conversion of Non-controlling Interest													8,000,000	0	0