CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ (49.2)	$ 81.0	$ 133.8	$ 13.1
Pension and other postretirement plans adjustments:
Amortization of prior service costs		0.0	0.1	0.0	0.2
Amortization of actuarial losses(1)	[1]	0.1		0.5	0.1
Net curtailment (1)	[2]		0.0		(0.3)
Other comprehensive income (loss)		0.1	0.1	0.5	0.0
Comprehensive income (loss)		$ (49.1)	$ 81.1	$ 134.3	$ 13.1

[1] Presented net of income tax benefit of $0.1 million and $0.2 million for the three and nine months ended September 30, 2020, respectively.

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