Note 2 - Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Revenues	$ 40,322	$ 54,614	$ 54,926	$ 48,634	$ 49,253	$ 46,138	$ 41,169	$ 41,660	$ 198,496	$ 178,220
Consolidation, Eliminations [Member]
Revenues									(137)	(7)
Heavy Fabrications [Member] | Operating Segments [Member]
Revenues									155,198	128,686
Gearing [Member] | Operating Segments [Member]
Revenues									25,136	34,877
Industrial Solutions [Member] | Operating Segments [Member]
Revenues									$ 18,299	$ 14,664