Note 3 - Revenue Recognition - Disaggregation of Revenues, Percentage (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Percentage of net sales	100.00%	100.00%
Hot Rolled Products [Member]
Percentage of net sales	32.30%	35.20%
Plate Products [Member]
Percentage of net sales	12.20%	12.90%
Cold Rolled Products [Member]
Percentage of net sales	5.50%	5.40%
Coated Products [Member]
Percentage of net sales	7.70%	7.40%
Specialty [Member]
Percentage of net sales	20.90%	20.00%
Pipe and Tube Products [Member]
Percentage of net sales	18.30%	17.40%
Product and Service, Other [Member]
Percentage of net sales	3.10%	1.70%
Carbon Flat Products [Member]
Percentage of net sales	58.70%	62.60%
Carbon Flat Products [Member] | Hot Rolled Products [Member]
Percentage of net sales	32.30%	35.20%
Carbon Flat Products [Member] | Plate Products [Member]
Percentage of net sales	12.20%	12.90%
Carbon Flat Products [Member] | Cold Rolled Products [Member]
Percentage of net sales	5.50%	5.40%
Carbon Flat Products [Member] | Coated Products [Member]
Percentage of net sales	7.70%	7.40%
Carbon Flat Products [Member] | Specialty [Member]
Percentage of net sales
Carbon Flat Products [Member] | Pipe and Tube Products [Member]
Percentage of net sales
Carbon Flat Products [Member] | Product and Service, Other [Member]
Percentage of net sales	1.00%	1.70%
Specialty Metals Flat Products [Member]
Percentage of net sales	23.00%	20.00%
Specialty Metals Flat Products [Member] | Hot Rolled Products [Member]
Percentage of net sales
Specialty Metals Flat Products [Member] | Plate Products [Member]
Percentage of net sales
Specialty Metals Flat Products [Member] | Cold Rolled Products [Member]
Percentage of net sales
Specialty Metals Flat Products [Member] | Coated Products [Member]
Percentage of net sales
Specialty Metals Flat Products [Member] | Specialty [Member]
Percentage of net sales	20.90%	20.00%
Specialty Metals Flat Products [Member] | Pipe and Tube Products [Member]
Percentage of net sales
Specialty Metals Flat Products [Member] | Product and Service, Other [Member]
Percentage of net sales	2.10%	0.00%
Tubular and Pipe Products [Member]
Percentage of net sales	18.30%	17.40%
Tubular and Pipe Products [Member] | Hot Rolled Products [Member]
Percentage of net sales
Tubular and Pipe Products [Member] | Plate Products [Member]
Percentage of net sales
Tubular and Pipe Products [Member] | Cold Rolled Products [Member]
Percentage of net sales
Tubular and Pipe Products [Member] | Coated Products [Member]
Percentage of net sales
Tubular and Pipe Products [Member] | Specialty [Member]
Percentage of net sales
Tubular and Pipe Products [Member] | Pipe and Tube Products [Member]
Percentage of net sales	18.30%	17.40%
Tubular and Pipe Products [Member] | Product and Service, Other [Member]
Percentage of net sales