Supplemental Balance Sheet Information - Schedule of Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Trade Receivables, net
Allowance for doubtful receivables	$ (0.5)	$ (0.8)
Trade receivables, net	297.2	332.7
Inventories
Finished products	98.0	90.3
Work-in-process	242.5	162.2
Raw materials	174.0	143.0
Operating supplies	10.9	9.1
Total	525.4	404.6
Property, Plant and Equipment, net
Land and improvements	28.4	26.0
Buildings and leasehold improvements	185.5	179.0
Machinery and equipment	1,232.7	1,151.5
Construction in progress	141.3	75.3
Property, plant and equipment, gross	1,587.9	1,431.8
Accumulated depreciation and amortization	(574.9)	(480.4)
Assets held for sale	0.2	3.8
Property, plant and equipment, net	1,013.2	955.2
Other Accrued Liabilities
Uncleared cash disbursements	13.6	10.9
Accrued income taxes and other taxes payable	8.9	9.5
Accrued interest	9.9	9.9
Short-term environmental accrual - Note 10	1.1	2.6
Other - Note 3 and Note 8	34.9	25.5
Total	68.4	58.4
Long-Term Liabilities
Workers' compensation accruals	30.9	31.9
Long-term environmental accrual	16.6	14.2
Other long-term liabilities	27.2	26.4
Total	74.7	72.5
Billed
Trade Receivables, net
Billed trade receivables	$ 297.7	$ 333.5