STATEMENTS OF CONSOLIDATED CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net income (loss)	$ 46.8	$ 47.2	$ (29.6)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation of property, plant and equipment	111.9	103.3	97.6
Amortization of definite-lived intangible assets	4.5	5.3	9.3
Amortization of debt premium and debt issuance costs	2.3	2.2	2.3
Deferred income taxes	6.8	7.5	(12.0)
LIFO valuation inventory expense	3.5	1.0	22.0
Non-cash equity compensation	14.4	16.1	14.3
Non-cash asset impairment charges	3.6		23.7
Gain on disposition of property, plant and equipment	(3.3)	(13.8)	(6.0)
Gain on reimbursement on certain machinery and equipment - Note 13			(6.0)
Bad debt expense	0.3
Non-cash postretirement and postemployment defined benefit plan cost	9.0	13.4	13.1
Changes in operating assets and liabilities:
Trade and other receivables	(4.4)	33.1	15.0
Contract assets	(14.9)	0.1	4.6
Inventories (excluding LIFO adjustments)	(29.4)	47.2	(142.8)
Prepaid expenses and other current assets	(9.6)	(2.8)	(1.5)
Accounts payable	14.1	(43.0)	(61.2)
Accrued liabilities	10.0	6.6	4.4
Annual variable cash contributions to Salaried VEBA	(1.1)
Long-term assets and liabilities, net	2.6	(11.5)	(10.3)
Net cash provided by (used in) operating activities	167.1	211.9	(63.1)
Cash flows from investing activities:
Capital expenditures	(180.8)	(143.2)	(142.5)
Purchase of equity securities	(0.1)	(0.3)	(0.3)
Proceeds from sale of equity securities	0.3	0.1
Proceeds from reimbursement on certain machinery and equipment - Note 13			6.0
Proceeds from disposition of property, plant and equipment	6.0	15.2	11.0
Net cash used in investing activities	(174.6)	(128.2)	(125.8)
Cash flows from financing activities:
Borrowings under the Revolving Credit Facility		215.1
Repayment of borrowings under the Revolving Credit Facility		(215.1)
Cash paid for debt issuance costs			(1.8)
Repayment of finance lease	(2.5)	(2.1)	(2.1)
Cancellation of shares to cover tax withholdings upon common shares issued	(2.1)	(1.8)	(2.8)
Cash dividends and dividend equivalents paid	(50.7)	(50.4)	(50.1)
Net cash used in financing activities	(55.3)	(54.3)	(56.8)
Net (decrease) increase in cash, cash equivalents and restricted cash during the period	(62.8)	29.4	(245.7)
Cash, cash equivalents and restricted cash at beginning of period	100.7	71.3	317.0
Cash, cash equivalents and restricted cash at end of period	$ 37.9	$ 100.7	$ 71.3