CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 81.0	$ 7.3		$ 13.1		$ (382.3)
Fair value of plan assets adjustment(1)	0.0	0.0		0.0		0.3	[1]
Pension and other postretirement plans adjustments:
Amortization of prior service costs(2)	0.1	0.2	[2]	0.2		0.4	[2]
Amortization of actuarial losses(3)	0.0	0.1	[3]	0.1		0.5	[3]
Curtailment Gain (Loss), after Tax(4)		0.0		(0.3)	[4]	0.0
Other comprehensive income (loss)	0.1	0.3		0.0		1.2
Comprehensive income (loss)	81.1	7.6		13.1		(381.1)
Amortization of prior service cost, income tax expense	$ 0.0	$ 0.0	[2]	$ 0.0		$ 0.1	[2]

[1] Adjustment recorded during the nine months ended September 30, 2018, related to a change in the fair value of plan assets as of December 31, 2017.

[2] Presented net of income tax expense of $0.1 million for the nine months ended September 30, 2018.

[3] Presented net of income tax benefit of $0.1 million and expense of $0.1 million for the three and nine months ended September 30, 2018, respectively.

[4] Presented net of income tax benefit of $0.1 million for the nine months ended September 30, 2019