Summary of Significant Accounting Policies, Textuals (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounting policies additional disclosures
Advertising costs	$ 1.3	$ 0.4	$ 0.4
Research and development costs	7.8	6.4	6.1
Net non-cash LIFO benefits	24.1	4.9	7.1
Excess of current cost over the stated LIFO value of inventory	0.4	24.5
Effect of LIFO Inventory Liquidation on Income		22.3
Impairment of the carrying value of goodwill	0	0
Discount rate used in estimating liabilities for worker compensation claims	1.75%	0.75%
Undiscounted workers' compensation liabilities	29.1	27.3
Margin deposits with counterparties	0	0
Margin deposits from counterparties	0	0
Performance shares
Accounting policies additional disclosures
Performance award vesting period, years	3 years
Fabricated Products
Accounting policies additional disclosures
Net non-cash LIFO benefits	$ 24.1	$ 4.9	$ 7.1
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
Number of days to maturity for debt investment securities to be classified as cash and cash equivalents	90 days
Period over which accounts receivable is due, days	60 days