Note 6 - Commitments and Contingencies (Details Textual) - USD ($) $ in Thousands		12 Months Ended
	Dec. 14, 2020	Dec. 31, 2020	Dec. 31, 2019
Gain (Loss) Related to Litigation Settlement, Total		$ 1,593	$ (0)
Capital Addition Purchase Commitments [Member]
Long-term Purchase Commitment, Amount		$ 873
Lithium Ion Batteries Antitrust Litigation [Member]
Litigation Settlement, Amount Awarded from Other Party	$ 1,593
Gain (Loss) Related to Litigation Settlement, Total	$ 1,593