Note 8 - Derivative Instruments - Impact from Derivatives on Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Gain (Loss) Recognized	$ (202)	$ (9)
Interest Rate Swap [Member]
Net Gain (Loss) Recognized	(202)	(9)
Metal Swaps [Member]
Net Gain (Loss) Recognized	(112)	130
Embedded Customer Derivatives [Member]
Net Gain (Loss) Recognized	$ 112	$ (130)