Supplemental Guarantor Financial Information - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 20.0	$ 22.5	$ 15.7
Restricted Cash, Current	1.4	0.0	0.0
Receivables, net of allowance for doubtful accounts of $1.5 at December 31, 2019 and 2018	159.1	145.5
Taxes receivable	0.3	6.3
Inventories	281.4	266.2
Other assets, current	3.6	3.4
Total current assets	465.8	443.9
Property, plant and equipment, net	1,257.7	1,269.3
Operating lease, right-of-use assets	73.1	0.0
Goodwill and intangible assets, net	52.0	59.2	276.7
Investment in subsidiary		0.0
Other assets, net	29.1	15.7
TOTAL ASSETS	1,877.7	1,788.1	$ 1,802.3
Current liabilities:
Short-term debt	17.9	122.2
Accounts payable and accrued liabilities	262.5	327.0
Total current liabilities	280.4	449.2
Long-term debt	884.5	692.9
Long-term operating lease liabilities	65.6	0.0
Liability for pension and other postretirement employee benefits	76.6	78.2
Other long-term obligations	17.3	20.2
Deferred income tax liabilities, net	121.3	121.2
Deferred Tax Liabilities, Gross, Noncurrent	121.3	121.2
Liabilities	1,445.7	1,361.7
Accumulated other comprehensive loss, net of tax	(59.5)	(67.3)
Stockholders Equity Excluding Accumulated Other Comprehensive Income Loss	491.5	493.7
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	1,877.7	1,788.1
Issuer
Current assets:
Cash and cash equivalents	20.0	22.5
Restricted Cash, Current	1.4
Receivables, net of allowance for doubtful accounts of $1.5 at December 31, 2019 and 2018	140.1	128.0
Taxes receivable	0.3	16.7
Inventories	244.1	222.9
Other assets, current	3.4	3.3
Total current assets	409.3	393.4
Property, plant and equipment, net	1,188.4	1,192.7
Operating lease, right-of-use assets	68.2
Goodwill and intangible assets, net	35.1	36.2
Intercompany receivable (payable)	(75.3)	(62.9)
Investment in subsidiary	179.1	175.3
Other assets, net	28.2	14.8
TOTAL ASSETS	1,833.0	1,749.5
Current liabilities:
Short-term debt	17.9	122.2
Accounts payable and accrued liabilities	242.9	305.7
Total current liabilities	260.8	427.9
Long-term debt	884.5	692.9
Long-term operating lease liabilities	62.2
Liability for pension and other postretirement employee benefits	76.6	78.2
Other long-term obligations	16.4	19.3
Deferred income tax liabilities, net	100.5	104.8
Liabilities	1,401.0	1,323.1
Accumulated other comprehensive loss, net of tax	(59.5)	(67.3)
Stockholders Equity Excluding Accumulated Other Comprehensive Income Loss	491.5	493.7
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	1,833.0	1,749.5
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	0.0	0.0
Restricted Cash, Current	0.0
Receivables, net of allowance for doubtful accounts of $1.5 at December 31, 2019 and 2018	19.0	17.5
Taxes receivable	0.0	0.0
Inventories	40.0	48.4
Other assets, current	0.2	0.1
Total current assets	59.2	66.0
Property, plant and equipment, net	69.3	76.6
Operating lease, right-of-use assets	4.9
Goodwill and intangible assets, net	16.9	23.0
Intercompany receivable (payable)	72.6	57.8
Investment in subsidiary	0.0	0.0
Other assets, net	2.6	2.6
TOTAL ASSETS	225.5	226.0
Current liabilities:
Short-term debt	0.0	0.0
Accounts payable and accrued liabilities	19.6	31.7
Total current liabilities	19.6	31.7
Long-term debt	0.0	0.0
Long-term operating lease liabilities	3.4
Liability for pension and other postretirement employee benefits	0.0	0.0
Other long-term obligations	0.9	0.9
Deferred income tax liabilities, net	22.5	18.1
Liabilities	46.4	50.7
Accumulated other comprehensive loss, net of tax	0.0	0.0
Stockholders Equity Excluding Accumulated Other Comprehensive Income Loss	179.1	175.3
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	225.5	226.0
Eliminations
Current assets:
Cash and cash equivalents	0.0	0.0
Restricted Cash, Current	0.0
Receivables, net of allowance for doubtful accounts of $1.5 at December 31, 2019 and 2018	0.0	0.0
Taxes receivable	0.0	(10.4)
Inventories	(2.7)	(5.1)
Other assets, current	0.0	0.0
Total current assets	(2.7)	(15.5)
Property, plant and equipment, net	0.0	0.0
Operating lease, right-of-use assets	0.0
Goodwill and intangible assets, net	0.0	0.0
Intercompany receivable (payable)	2.7	5.1
Investment in subsidiary	(179.1)	(175.3)
Other assets, net	(1.7)	(1.7)
TOTAL ASSETS	(180.8)	(187.4)
Current liabilities:
Short-term debt	0.0	0.0
Accounts payable and accrued liabilities	0.0	(10.4)
Total current liabilities	0.0	(10.4)
Long-term debt	0.0	0.0
Long-term operating lease liabilities	0.0
Liability for pension and other postretirement employee benefits	0.0	0.0
Other long-term obligations	0.0	0.0
Deferred income tax liabilities, net	(1.7)	(1.7)
Liabilities	(1.7)	(12.1)
Accumulated other comprehensive loss, net of tax	0.0	0.0
Stockholders Equity Excluding Accumulated Other Comprehensive Income Loss	(179.1)	(175.3)
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ (180.8)	$ (187.4)