Financing Arrangements (Details) - USD ($)	Apr. 22, 2016	Dec. 31, 2016	Dec. 21, 2016	Dec. 31, 2015	Oct. 21, 2015	Aug. 13, 2015	Oct. 24, 2014
Line of Credit Facility [Line Items]
Long-term debt		$ 475,000,000		$ 468,100,000
Short-term debt		5,000,000		0
Capital lease agreement						$ 50,000,000
Foreign subsidiaries borrowings		42,400,000.0		800,000.0
Foreign subsidiaries bank guarantee amount		$ 9,900,000		$ 3,900,000
Ownership percentage of domestic subsidiaries		100.00%
Weighted average interest rate		5.73%		5.47%
Arkansas Development Finance Authority | Southwest Steel Processing LLC
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 11,000,000.0
Amount outstanding		$ 6,200,000
GH Electrotermia S.A.
Line of Credit Facility [Line Items]
Long-term debt			$ 8,900,000
Short-term debt			5,000,000
Foreign Line of Credit
Line of Credit Facility [Line Items]
Long-term debt		26,400,000		$ 0
Revolving credit facility
Line of Credit Facility [Line Items]
Long-term debt		132,800,000		169,000,000
Revolving credit facility | Amended Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 300,000,000.0
Amount outstanding	$ 35,000,000
Inventory advance rate	60.00%
Inventory advance rate reducing back to	50.00%
Term over which inventory advance rate reduces	36 months
Term over which basis spread on variable rate reduces	36 months
Term loan, period	7 years
Revolving credit facility | Amended Credit Agreement | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	3.50%
Revolving credit facility | Amended Credit Agreement | LIBOR | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.50%
Revolving credit facility | Amended Credit Agreement | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	2.50%
Revolving credit facility | Amended Credit Agreement | Prime lending rate | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.25%
Revolving credit facility | Amended Credit Agreement | Prime lending rate | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.25%
Revolving credit facility | Amendment Number One to Sixth Amended and Restated Credit Agreement
Line of Credit Facility [Line Items]
Inventory advance rate							50.00%
Unused borrowing capacity		106,200,000
Revolving credit facility, Canadian sub-limit | Amended Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 35,000,000.0
Revolving credit facility, Canadian sub-limit | Amended Credit Agreement | Canadian deposit offered rate | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.50%
Revolving credit facility, Canadian sub-limit | Amended Credit Agreement | Canadian deposit offered rate | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	2.50%
Revolving credit facility, Canadian sub-limit | Amended Credit Agreement | Canadian prime lending rate | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.00%
Revolving credit facility, Canadian sub-limit | Amended Credit Agreement | Canadian prime lending rate | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.00%
Revolving credit facility, Canadian sub-limit | Amended Credit Agreement | US base rate | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.00%
Revolving credit facility, Canadian sub-limit | Amended Credit Agreement | US base rate | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	1.00%
Revolving credit facility, European sub-limit | Amended Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 25,000,000.0
Term Loan
Line of Credit Facility [Line Items]
Long-term debt		23,400,000		$ 27,900,000
Term Loan | Amended Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 35,000,000.0
Term Loan | Amended Credit Agreement | LIBOR | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	2.00%
Term Loan | Amended Credit Agreement | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	3.00%
Term Loan | Amended Credit Agreement | Prime lending rate | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.75%
Term Loan | Amended Credit Agreement | Prime lending rate | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable interest rate	0.25%
Banco Bolbao Vizcaya Argentaria, S.A. | Line of Credit | Foreign Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity			36,900,000.0
Banco Bolbao Vizcaya Argentaria, S.A. | Line of Credit | Foreign Line of Credit | GH Electrotermia S.A. | Financing Agreement [Member]
Line of Credit Facility [Line Items]
Amount outstanding			26,400,000
Banco Bolbao Vizcaya Argentaria, S.A. | Line of Credit | Revolving credit facility | Financing Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 10,500,000.0
Amount outstanding		$ 0