EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income (loss)	$ 489.3	$ 52.7	$ (5.9)	$ 13.4	$ 17.5	$ 17.5	$ (1.0)	$ (37.9)	$ 549.5	$ (3.9)	$ (1.4)
Basic shares (in shares)									166.2	165.2	103.4
Earnings per Share, Basic [Abstract]
Basic net income (loss) per share (in dollars per share)	$ 2.93	$ 0.32	$ (0.04)	$ 0.08	$ 0.11	$ 0.11	$ (0.01)	$ (0.23)	$ 3.31	$ (0.02)	$ (0.01)
Earnings per Share, Diluted [Abstract]
Basic shares (in shares)									166.2	165.2	103.4
Stock-based compensation (in shares)									2.3	0.0	0.0
Diluted shares (in shares)									168.5	165.2	103.4
Diluted net (loss) income per share (in dollars per share)	$ 2.89	$ 0.31	$ (0.04)	$ 0.08	$ 0.10	$ 0.11	$ (0.01)	$ (0.23)	$ 3.26	$ (0.02)	$ (0.01)
Antidilutive shares excluded from the computation of earnings per share (in shares)									1.6	6.5	5.2