Note 9 - Earnings Per Share (Details) - Basic and diluted earnings per share (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Basic and diluted earnings per share [Abstract]
Net Loss from continuing operations attributable to Ultralife	$ (1,953)	$ (3,216)	$ (1,783)	$ (4,647)
Net Loss from continuing operations attributable to Ultralife common shareholders (a)	(1,953)	(3,216)	(1,783)	(4,647)
Net Loss from continuing operations attributable to Ultralife common shareholders - Adjusted (b)	(1,953)	(3,216)	(1,783)	(4,647)
Net Income (Loss) from discontinued operations attributable to Ultralife common shareholders (c)	(120)	49	144	(22)
Net Income (Loss) from discontinued operations attributable to Ultralife common shareholders - Adjusted (d)	$ (120)	$ 49	$ 144	$ (22)
Average Common Shares Outstanding – Basic (e) (in Shares)	17,459,000	17,396,000	17,458,000	17,376,000
Average Common Shares Outstanding – Diluted (f) (in Shares)	17,459,000	17,396,000	17,458,000	17,376,000
EPS – Basic (a/e) - continuing operations (in Dollars per share)	$ (0.11)	$ (0.18)	$ (0.10)	$ (0.27)
EPS – Basic (c/e) - discontinued operations (in Dollars per share)	$ (0.01)	$ 0.00	$ 0.01	$ 0.00
EPS – Diluted (b/f) - continuing operations (in Dollars per share)	$ (0.11)	$ (0.18)	$ (0.10)	$ (0.27)
EPS – Diluted (d/f) - discontinued operations (in Dollars per share)	$ (0.01)	$ 0.00	$ 0.01	$ 0.00