Note 8 - Derivative Instruments - Impact from Derivatives on Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivatives		$ (6)	$ (5)	$ (24)
Interest Rate Swap [Member] | Chicago Tube and Iron Company Acquisition [Member]
Derivatives		(6)	(5)	(24)
Metal Swaps [Member]
Derivatives	(221)	156	14	79
Embedded Customer Derivatives [Member]
Derivatives	$ 221	$ (156)	$ (14)	$ (79)