Note 13 - Segment Information - Segment Reporting Information by Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Capital expenditures:
Capital expenditures	$ 6,591	$ 2,001	$ 20,366	$ 6,470
Total assets	789,267		789,267		$ 604,158
Flat Products Segment [Member]
Capital expenditures:
Capital expenditures	4,980	1,110	15,289	4,292
Total assets	579,602		579,602		409,116
Tubular and Pipe Products [Member]
Capital expenditures:
Capital expenditures	1,505	891	4,598	2,178
Total assets	209,007		209,007		194,787
Corporate Segment [Member]
Capital expenditures:
Capital expenditures	106		479
Total assets	$ 658		$ 658		$ 255