Summary of Significant Accounting Policies, Narrative (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Accounting policies additional disclosures
Number of operating segments | segment									1
Advertising costs									$ 0.4	$ 1.2	$ 0.6
Research and development costs									10.2	9.5	8.9
Lower of cost or market inventory write-down	$ 0.0	$ 0.0	$ 0.0	$ 4.9	$ 2.6	$ 0.0	$ 0.0	$ 0.0	4.9	2.6	0.0
Excess of current cost over the stated LIFO value of inventory	(8.5)				(24.1)				(8.5)	(24.1)
Non-cash impairment charges									2.8	0.1	$ 1.5
Impairment of the carrying value of goodwill	0.0				0.0				0.0	0.0
Undiscounted workers' compensation liabilities	26.8				23.5				$ 26.8	$ 23.5
Discount rate used in estimating liabilities for worker compensation claims									2.00%	1.75%
Accrued employee healthcare benefits	3.6				$ 3.2				$ 3.6	$ 3.2
Minimum
Accounting policies additional disclosures
Period over which accounts receivable is due, days									30 days
Number of days in maturity for debt investment securities to be classified as short-term investments									90 days
Maximum
Accounting policies additional disclosures
Period over which accounts receivable is due, days									60 days
Number of days to maturity for debt investment securities to be classified as cash and cash equivalents									90 days
Adjustments for New Accounting Pronouncement [Member]
Accounting policies additional disclosures
Debt Issuance Costs, Net	$ 3.2								$ 3.2