Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of Reportable Segments	3
LIFO Inventory Amount	$ 43.4	$ 42.7
Percentage of LIFO Inventory	17.10%	20.70%
Minimum [Member]
Property, Plant and Equipment, Useful Life	2 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	30 years
Steel Requirements [Member] \| Supplier Concentration Risk [Member] \| Three Largest Suppliers [Member]
Concentration Risk, Percentage	54.00%	51.00%	43.00%
Sales Revenue, Goods, Net [Member] \| Customer Concentration Risk [Member] \| Top 20 [Member]
Concentration Risk, Percentage	29.00%	31.00%	29.00%
Sales Revenue, Goods, Net [Member] \| Customer Concentration Risk [Member] \| Largest Customer [Member]
Concentration Risk, Percentage	4.00%	6.00%	6.00%
Sales Revenue, Goods, Net [Member] \| Customer Concentration Risk [Member] \| Industrial Machinery and Equipment Manufacturers and Fabricators [Member]
Concentration Risk, Percentage	51.00%	49.00%	51.00%
Sales Revenue, Goods, Net [Member] \| Product Concentration Risk [Member] \| Engineered Products [Member]
Concentration Risk, Percentage	1.70%	1.80%	1.70%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6361739&loc=d3e7789-107766

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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