Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Reportable Segments	3
LIFO Inventory Amount	$ 39.1	$ 51.1
Percentage of LIFO Inventory	14.30%	13.90%
Software and Software Development Costs [Member]
Property, Plant and Equipment, Useful Life	5 years
Minimum [Member]
Property, Plant and Equipment, Useful Life	2 years
Minimum [Member] \| Software and Software Development Costs [Member]
Property, Plant and Equipment, Useful Life	2 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	30 years
Maximum [Member] \| Software and Software Development Costs [Member]
Property, Plant and Equipment, Useful Life	5 years
Steel Requirements [Member] \| Supplier Concentration Risk [Member] \| Three Largest Suppliers [Member]
Concentration Risk, Percentage	57.00%	52.00%	53.00%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| Top 20 [Member]
Concentration Risk, Percentage	29.00%	29.00%	27.00%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| Largest Customer [Member]
Concentration Risk, Percentage	5.00%	5.00%	4.00%
Revenue Benchmark [Member] \| Customer Concentration Risk [Member] \| Industrial Machinery and Equipment Manufacturers and Fabricators [Member]
Concentration Risk, Percentage	46.00%	48.00%	51.00%

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.

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