Supplemental Data (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment - Net
Gross property, plant and equipment	$ 755.6	$ 694.5
Less accumulated depreciation	391.0	371.5
Net Property, Plant and Equipment	364.6	323.0
Depreciation expense	27.1	24.8	$ 23.2
Interest expense capitalized	0.8	0.2	$ 0.1
Accrued Expenses
Accrued salaries and employee benefits	26.3	25.2
Amounts due to customers	7.3	9.5
Accrued interest	1.3	1.2
Accrued income taxes	2.0	0.7
Other	14.3	14.6
Total	51.2	51.2
Noncurrent Employee Benefits
Pension benefits	49.0	51.2
Post-employment benefits other than pensions	37.7	38.5
Total	86.7	89.7
Long-term disability benefits due to Terrace Bay retirees	1.3	2.7
Land and land improvements
Property, Plant and Equipment - Net
Gross property, plant and equipment	18.3	19.6
Buildings
Property, Plant and Equipment - Net
Gross property, plant and equipment	126.1	121.4
Machinery and equipment
Property, Plant and Equipment - Net
Gross property, plant and equipment	597.5	512.2
Construction in progress
Property, Plant and Equipment - Net
Gross property, plant and equipment	$ 13.7	$ 41.3