Note 2 - Acquisitions (Details Textual) - USD ($) $ in Thousands			3 Months Ended	9 Months Ended		12 Months Ended
	Mar. 31, 2021	Jan. 08, 2021	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Payments to Acquire Businesses, Net of Cash Acquired, Total				$ 16,811	$ (0)
Goodwill, Ending Balance			$ 25,846	25,846		$ 23,966
EOS Power Panama Inc. [Member]
Revenues, Total						$ 12,000
Business Combination, Acquisition Related Costs			0	500
rms Connectors, Inc. [Member]
Payments to Acquire Businesses, Net of Cash Acquired, Total		$ 9,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred	$ (7,800)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		0
Goodwill, Ending Balance		$ 0
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual			4,300	12,400
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual			200	1,600
EOS Power Panama Inc. [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	2,000		2,000	2,000
Goodwill, Ending Balance	$ 2,659
EOS Power Panama Inc. [Member] | Customer Relationships [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			$ 1,800	1,800
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)			16 years
EOS Power Panama Inc. [Member] | Trade Names [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			$ 200	$ 200
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)			2 years