Financing Arrangements (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 30, 2017	Oct. 21, 2015	Aug. 13, 2015
Line of Credit Facility [Line Items]
Percentage ownership	100.00%
Finance lease agreement, amount								$ 50,000,000
Finance leases		$ 17,500,000	$ 18,700,000
Foreign subsidiaries borrowings amount		9,800,000	13,000,000
Foreign subsidiaries bank guarantee amount		$ 39,700,000	$ 34,900,000
Weighted average interest rate		5.20%	5.40%	5.80%
Arkansas Development Finance Authority | Southwest Steel Processing LLC
Line of Credit Facility [Line Items]
Maximum borrowing capacity							$ 11,000,000
Credit facility outstanding		$ 5,800,000
Senior Notes due 2027 | Senior Notes
Line of Credit Facility [Line Items]
Aggregate principal amount						$ 350,000,000
Stated interest rate		6.625%				6.625%
Revolving credit facility
Line of Credit Facility [Line Items]
Stated interest rate		1.30%
Revolving credit facility | Seventh Amendment Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 375,000,000
Accordion feature, increase limit					100,000,000
Line of credit facility, remaining borrowing capacity		$ 138,800,000
Revolving credit facility, Canadian sub-limit | Seventh Amendment Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity					40,000,000
Revolving credit facility, European sub-limit | Seventh Amendment Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 30,000,000