Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Cash and Cash Equivalents
Cash and money market funds	$ 29.3	$ 22.9
Commercial paper	142.8	102.7
Total	172.1	125.6
Trade Receivables – Net
Trade receivables, gross	188.9	180.6
Allowance for doubtful receivables	(0.8)	(0.8)
Trade receivables – net	188.1	179.8
Inventories
Finished products	41.4	48.0
Work-in-process	80.5	85.6
Raw materials	63.7	75.0
Operating supplies	6.9	6.5
Total	192.5	215.1
Property, Plant and Equipment – Net
Land and improvements	21.4	21.4
Buildings and leasehold improvements	99.2	97.0
Machinery and equipment	797.9	755.6
Construction in progress	35.4	43.6
Property, plant and equipment – gross	953.9	917.6
Accumulated depreciation	(341.2)	(307.4)
Assets held for sale	1.6	1.6
Property, plant and equipment – net	614.3	611.8
Other Accrued Liabilities
Uncleared cash disbursements	3.7	4.8
Accrued income taxes and taxes payable	8.0	6.5
Accrued annual contribution to Salaried VEBA	0.0	2.1
Accrued interest	8.4	2.9
Accrued environmental	4.3	2.6
Other	25.7	25.1
Total	50.1	44.0
Long-Term Liabilities
Workers’ compensation accruals	26.9	24.6
Long-term environmental accrual	12.2	14.3
Other long-term liabilities	26.3	27.5
Total	65.4	66.4
Billed
Trade Receivables – Net
Trade receivables, gross	188.9	179.5
Unbilled
Trade Receivables – Net
Trade receivables, gross	$ 0.0	$ 1.1