STATEMENTS OF CONSOLIDATED CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net income	$ 24.6	$ 15.9
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation of property, plant and equipment	27.7	24.9
Amortization of definite-lived intangible assets	1.1	1.4
Amortization of debt premium and debt issuance costs	0.6	0.5
Amortization of cloud computing implementation costs	0.3	0.4
Deferred income taxes	6.8	4.1
Non-cash equity compensation	4.0	3.4
Non-cash asset impairment charge	4.2
Loss (gain) on disposition of property, plant and equipment	0.2	(15.0)
Bad debt expense	0.1
Non-cash postretirement benefit plan costs	1.5	3.1
Changes in operating assets and liabilities:
Trade and other receivables	(15.1)	(36.9)
Contract assets	(4.5)	5.7
Inventories	4.4	(12.3)
Prepaid expenses and other current assets	(1.7)	(1.3)
Accounts payable	18.6	(22.6)
Accrued liabilities	(5.2)	10.3
Annual variable cash contributions to Salaried VEBA	(1.1)
Long-term assets and liabilities, net	(3.2)	(1.9)
Net cash provided by (used in) operating activities	63.3	(20.3)
Cash flows from investing activities:
Capital expenditures	(30.0)	(41.1)
Proceeds from sale of equity securities	0.1
Proceeds from disposition of property, plant and equipment		15.2
Net cash used in investing activities	(29.9)	(25.9)
Cash flows from financing activities:
Borrowings under the Revolving Credit Facility		119.5
Repayment of borrowings under the Revolving Credit Facility		(80.1)
Repayment of finance lease	(0.4)	(0.6)
Cancellation of shares to cover tax withholdings upon common shares issued	(1.2)	(1.3)
Cash dividends and dividend equivalents paid	(12.6)	(12.5)
Net cash (used in) provided by financing activities	(14.2)	25.0
Net increase (decrease) in cash, cash equivalents and restricted cash during the period	19.2	(21.2)
Cash, cash equivalents and restricted cash at beginning of period	100.7	71.3
Cash, cash equivalents and restricted cash at end of period	$ 119.9	$ 50.1