Note 9 - Earnings Per Share (Details) - Basic and diluted earnings per share (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2013	Sep. 30, 2012	Sep. 29, 2013	Sep. 30, 2012
Basic and diluted earnings per share [Abstract]
Net Income (Loss) from continuing operations attributable to Ultralife common shareholders (a) (in Dollars)	$ 629	$ 1,479	$ (1,154)	$ (3,169)
Net Income (Loss) from continuing operations attributable to Ultralife common shareholders - Adjusted (b) (in Dollars)	629	1,479	(1,154)	(3,169)
Net Income from discontinued operations attributable to Ultralife common shareholders (c) (in Dollars)	15	200	159	178
Net Income from discontinued operations attributable to Ultralife common shareholders - Adjusted (d) (in Dollars)	$ 15	$ 200	$ 159	$ 178
Average Common Shares Outstanding – Basic (e) (in Shares)	17,467,000	17,418,000	17,461,000	17,390,000
Effect of Dilutive Securities:
Stock Options / Warrants (in Shares)	65,000
Average Common Shares Outstanding – Diluted (f) (in Shares)	17,532,000	17,418,000	17,461,000	17,390,000
EPS – Basic (a/e) - continuing operations	$ 0.04	$ 0.09	$ (0.07)	$ (0.18)
EPS – Basic (c/e) - discontinued operations	$ 0.00	$ 0.01	$ 0.01	$ 0.01
EPS – Diluted (b/f) - continuing operations	$ 0.04	$ 0.09	$ (0.07)	$ (0.18)
EPS – Diluted (d/f) - discontinued operations	$ 0.00	$ 0.01	$ 0.01	$ 0.01