Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents
Cash and money market funds	$ 23.5	$ 37.9
Commercial paper	10.9	17.3
Total	34.4	55.2
Trade Receivables – Net
Trade receivables, gross	158.1	138.5
Allowance for doubtful receivables	(1.1)	(0.8)
Trade receivables – net	157.0	137.7
Inventories
Finished products	68.4	73.8
Work-in-process	75.3	71.7
Raw materials	54.7	51.1
Operating supplies	5.1	5.0
Total	203.5	201.6
Property, Plant and Equipment – Net
Land and improvements	22.7	22.7
Buildings and leasehold improvements	89.0	88.6
Machinery and equipment	620.8	615.1
Construction in progress	42.3	34.8
Property, plant and equipment – gross	774.8	761.2
Accumulated depreciation	(239.3)	(230.6)
Assets held for sale	0.3	0.3
Property, plant and equipment – net	535.8	530.9
Other Accrued Liabilities
Uncleared cash disbursements	4.6	5.8
Accrued income taxes and taxes payable	9.5	4.3
Accrued annual contribution to VEBAs	11.5	20.0
Accrued interest	8.4	2.9
Other	6.4	7.1
Total	40.4	40.1
Long-Term Liabilities
Workers’ compensation accruals	24.5	25.0
Long-term environmental accrual	15.8	15.8
Long-term portion of contingent contribution to Union VEBA	0.0	12.8
Other long-term liabilities	19.8	19.6
Total	60.1	73.2
Billed
Trade Receivables – Net
Trade receivables, gross	157.6	138.2
Unbilled
Trade Receivables – Net
Trade receivables, gross	$ 0.5	$ 0.3