Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 21.4	$ (11.0)	$ 54.5	$ (7.6)
Depreciation and amortization	27.7	32.0	83.5	86.3
Stock-based compensation expense	2.5	0.9	7.3	3.0
Deferred taxes	12.8	(11.2)	23.5	(6.0)
Pension and other postretirement employment benefits	0.9	0.7	2.9	1.0
Debt retirement costs	3.9	2.7	4.8	2.7
Gain on divested assets	0.0	0.0	1.4	0.0
(Increase) decrease in accounts receivable	12.8	13.4	(5.7)	(12.5)
(Increase) decrease in inventory	(21.0)	4.0	25.0	(21.1)
(Increase) decrease in other current assets	0.6	0.6	(4.8)	(5.2)
Increase (decrease) in trade payables	4.1	(54.4)	(16.2)	(61.7)
Increase (decrease) in accrued compensation	(0.5)	0.1	5.1	(4.0)
Increase (decrease) in other accrued liabilities	(9.3)	(10.5)	(3.3)	5.8
Other, net	(0.1)	1.8	0.8	3.0
Net cash flows provided by (used in) operating activities	55.7	(31.0)	176.1	(16.2)
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to property, plant and equipment	(9.7)	(17.4)	(27.5)	(125.8)
Net cash flows used in investing activities	(9.7)	(17.4)	(27.5)	(125.8)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings of short-term debt	0.0	98.0	108.5	534.9
Repayments of short-term debt	0.0	(276.0)	(122.0)	(598.7)
Borrowings of long-term debt	275.0	296.1	275.0	296.1
Repayments of long-term debt	(317.6)	(101.7)	(379.0)	(101.7)
Payments for debt issuance costs	(4.3)	(1.8)	(4.3)	(1.8)
Other, net	0.2	(0.3)	(0.7)	(1.4)
Net cash flows provided by (used in) financing activities	(46.7)	14.3	(122.5)	127.4
Increase (decrease) in cash, cash equivalents and restricted cash	(0.6)	(34.0)	26.1	(14.7)
Cash, cash equivalents and restricted cash at beginning of period	49.2	44.3	22.4	24.9
Cash, cash equivalents and restricted cash at end of period	48.6	10.3	48.6	10.3
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest, net of amounts capitalized	19.5	22.4	43.6	38.8
Cash (received) paid for income taxes	(4.7)	0.3	(6.9)	2.0
Total cash, cash equivalents and restricted cash	$ 48.6	$ 10.3	$ 48.6	$ 10.3