Note 2 - Acquisition - Pro Forma Information (Details) - Southwest Electronic Energy Corporation [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue	$ 107,712	$ 115,590
Operating income	5,701	8,008
Net Income attributable to Ultralife Corporation	$ 5,232	$ 5,526
Basic (in dollars per share)	$ 0.33	$ 0.35
Diluted (in dollars per share)	$ 0.33	$ 0.34