Note 10 - Derivative Instruments - Impact from Derivatives on Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Gain (Loss) Recognized	$ (227)	$ (5)	$ (31)
Interest Rate Swap [Member]
Net Gain (Loss) Recognized	(227)
Interest Rate Swap [Member] | Chicago Tube and Iron Company Acquisition [Member]
Net Gain (Loss) Recognized		(5)	(31)
Metal Swaps [Member]
Net Gain (Loss) Recognized	291	(79)	475
Embedded Customer Derivatives [Member]
Net Gain (Loss) Recognized	$ (291)	$ 79	$ (475)