Note 11 - Business Segment Information - Revenue by Business Segment Sector (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Revenues	[1]	$ 30,373	$ 25,973
Commercial [Member]
Revenues		$ 23,260	$ 14,345
Revenue, percentage		77.00%	55.00%
Government & Defense [Member]
Revenues		$ 7,113	$ 11,628
Revenue, percentage		23.00%	45.00%
Battery & Energy Products Segment [Member]
Revenues	[1]	$ 29,150	$ 22,111
Battery & Energy Products Segment [Member] | Commercial [Member]
Revenues		23,260	14,345
Battery & Energy Products Segment [Member] | Government & Defense [Member]
Revenues		5,890	7,766
Communications Systems Segment [Member]
Revenues	[1]	1,223	3,862
Communications Systems Segment [Member] | Commercial [Member]
Revenues		0	0
Communications Systems Segment [Member] | Government & Defense [Member]
Revenues		$ 1,223	$ 3,862

[1] Sales classified to U.S. include shipments to U.S.-based prime contractors which in some cases may serve non-U.S. projects.