Note 13 - Segment Information - Segment Reporting Information by Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net sales:
Net sales	$ 456,976	$ 331,442	$ 1,285,491	$ 1,022,530
Depreciation and amortization:
Depreciation and amortization	4,200	4,106	12,857	13,183
Operating income (loss):
Operating income	18,614	5,286	55,278	25,970
Other income (loss), net	17	(22)	(122)	(76)
Income before interest and income taxes	18,631	5,264	55,156	25,894
Interest and other expense on debt	2,923	1,966	7,579	5,380
Income before income taxes	15,708	3,298	47,577	20,514
Carbon Flat Products [Member]
Net sales:
Net sales	282,810	215,843	802,995	669,817
Depreciation and amortization:
Depreciation and amortization	2,524	2,493	7,665	8,287
Operating income (loss):
Operating income	14,493	3,698	40,901	18,312
Specialty Metals Flat Products [Member]
Net sales:
Net sales	92,153	57,554	255,037	173,789
Depreciation and amortization:
Depreciation and amortization	341	185	880	609
Operating income (loss):
Operating income	4,954	2,074	13,493	8,918
Tubular and Pipe Products [Member]
Net sales:
Net sales	82,013	58,045	227,459	178,924
Depreciation and amortization:
Depreciation and amortization	1,311	1,403	4,237	4,211
Operating income (loss):
Operating income	3,102	1,608	11,917	6,439
Corporate Segment [Member]
Depreciation and amortization:
Depreciation and amortization	24	25	75	76
Operating income (loss):
Operating income	$ (3,935)	$ (2,094)	$ (11,033)	$ (7,699)