Supplemental Balance Sheet Information - Schedule of Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Trade Receivables, Net
Allowance for doubtful receivables	$ (0.6)	$ (0.8)
Trade receivables, net	311.5	332.7
Inventories
Finished products	88.1	90.3
Work-in-process	229.6	162.2
Raw materials	208.6	143.0
Operating supplies	11.8	9.1
Total	538.1	404.6
Property, Plant and Equipment, Net
Land and improvements	28.4	26.0
Buildings and leasehold improvements	184.2	179.0
Machinery and equipment	1,190.6	1,151.5
Construction in progress	136.6	75.3
Property, plant and equipment, gross	1,539.8	1,431.8
Accumulated depreciation and amortization	(550.4)	(480.4)
Assets held for sale	0.2	3.8
Property, plant and equipment, net	989.6	955.2
Other Accrued Liabilities
Uncleared cash disbursements	19.8	10.9
Accrued income taxes and other taxes payable	11.0	9.5
Accrued interest	10.3	9.9
Short-term environmental accrual	1.8	2.6
Short-term operating lease liabilities	9.3	9.0
Other - Note 4	36.3	16.5
Total	88.5	58.4
Long-Term Liabilities
Workers' compensation accrual	31.5	31.9
Long-term environmental accrual	13.1	14.2
Other long-term liabilities	27.6	26.4
Total	72.2	72.5
Billed
Trade Receivables, Net
Billed trade receivables	$ 312.1	$ 333.5