Note 2 - Revenue Recognition - Disaggregation of Revenues, Percentage (Details)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Percentage of net sales	100.00%	100.00%
Hot Rolled Products [Member]
Percentage of net sales	30.00%	35.40%
Plate Products [Member]
Percentage of net sales	11.60%	13.20%
Cold Rolled Products [Member]
Percentage of net sales	5.60%	5.50%
Coated Products [Member]
Percentage of net sales	8.60%	7.00%
Specialty [Member]
Percentage of net sales	25.00%	17.80%
Tube Products [Member]
Percentage of net sales	17.80%	17.80%
Product and Service, Other [Member]
Percentage of net sales	1.40%	3.30%
Carbon Flat Products [Member]
Percentage of net sales	57.20%	62.40%
Carbon Flat Products [Member] | Hot Rolled Products [Member]
Percentage of net sales	30.00%	35.40%
Carbon Flat Products [Member] | Plate Products [Member]
Percentage of net sales	11.60%	13.20%
Carbon Flat Products [Member] | Cold Rolled Products [Member]
Percentage of net sales	5.60%	5.50%
Carbon Flat Products [Member] | Coated Products [Member]
Percentage of net sales	8.60%	7.00%
Carbon Flat Products [Member] | Specialty [Member]
Percentage of net sales	0.00%	0.00%
Carbon Flat Products [Member] | Tube Products [Member]
Percentage of net sales	0.00%	0.00%
Carbon Flat Products [Member] | Product and Service, Other [Member]
Percentage of net sales	1.40%	1.30%
Specialty Metals Flat Products [Member]
Percentage of net sales	25.00%	19.80%
Specialty Metals Flat Products [Member] | Hot Rolled Products [Member]
Percentage of net sales	0.00%	0.00%
Specialty Metals Flat Products [Member] | Plate Products [Member]
Percentage of net sales	0.00%	0.00%
Specialty Metals Flat Products [Member] | Cold Rolled Products [Member]
Percentage of net sales	0.00%	0.00%
Specialty Metals Flat Products [Member] | Coated Products [Member]
Percentage of net sales	0.00%	0.00%
Specialty Metals Flat Products [Member] | Specialty [Member]
Percentage of net sales	25.00%	17.80%
Specialty Metals Flat Products [Member] | Tube Products [Member]
Percentage of net sales	0.00%	0.00%
Specialty Metals Flat Products [Member] | Product and Service, Other [Member]
Percentage of net sales	0.00%	2.00%
Tubular and Pipe Products [Member]
Percentage of net sales	17.80%	17.80%
Tubular and Pipe Products [Member] | Hot Rolled Products [Member]
Percentage of net sales	0.00%	0.00%
Tubular and Pipe Products [Member] | Plate Products [Member]
Percentage of net sales	0.00%	0.00%
Tubular and Pipe Products [Member] | Cold Rolled Products [Member]
Percentage of net sales	0.00%	0.00%
Tubular and Pipe Products [Member] | Coated Products [Member]
Percentage of net sales	0.00%	0.00%
Tubular and Pipe Products [Member] | Specialty [Member]
Percentage of net sales	0.00%	0.00%
Tubular and Pipe Products [Member] | Tube Products [Member]
Percentage of net sales	17.80%	17.80%
Tubular and Pipe Products [Member] | Product and Service, Other [Member]
Percentage of net sales	0.00%	0.00%