CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS)	$ (347.4)	$ 72.7	$ 320.6
OTHER COMPREHENSIVE INCOME (LOSS)
Net changes in pension and other postretirement plan assets and benefit obligations recognized in other comprehensive income (loss), net of income tax expense (benefit) of $(4.8), $0, and $(2.8), respectively.	(17.9)	(33.3)	(5.1)
Net reclassification adjustment for amounts recognized in net income (loss) as a component of net periodic benefit cost, net of income tax expense (benefit) of $(1.5), $0, and $3.8, respectively.	(5.6)	11.4	7.4
OTHER COMPREHENSIVE INCOME (LOSS)	(23.5)	(21.9)	2.3
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ (370.9)	$ 50.8	$ 322.9