CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions		12 Months Ended
	Aug. 10, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS)		$ 320.6	$ 93.3	$ (114.9)
OTHER COMPREHENSIVE INCOME (LOSS)
Net changes in pension and other postretirement plan assets and benefit obligations recognized in other comprehensive income, net of income tax expense (benefit) of $(2.8), $3.4, and ($47.0), respectively	$ 19.2	(5.1)	7.0	(87.3)
Net reclassification adjustments for amounts recognized in net income (loss) as a component of net periodic benefit cost, net of income tax expense of $3.8, $7.4, and $5.3, respectively		7.4	13.8	9.8
OTHER COMPREHENSIVE INCOME (LOSS)		2.3	20.8	(77.5)
COMPREHENSIVE INCOME (LOSS)		$ 322.9	$ 114.1	$ (192.4)