Note 11 - Business Segment Information (Details) - Components of segment performance (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2013	Sep. 30, 2012	Sep. 29, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 20,361	$ 26,181	$ 58,659	$ 72,388
Segment contribution	652	1,754	(847)	(2,468)
Interest expense, net	(53)	(96)	(172)	(312)
Miscellaneous	(8)	(15)	(31)	17
Income taxes-current	19	(120)	(42)	(387)
Income taxes-deferred	(3)	(55)	(93)	(50)
Income/loss from discontinued operations	15	200	159	178
Noncontrolling interest	22	11	31	31
Net income/loss attributable to Ultralife	644	1,679	(995)	(2,991)
Total assets	88,675	95,329	88,675	95,329	97,718
Battery & Energy Products [Member]
Segment Reporting Information [Line Items]
Revenues	13,507	16,633	41,216	52,238
Segment contribution	3,601	4,770	10,191	12,476
Total assets	42,679	54,031	42,679	54,031
Communications Systems [Member]
Segment Reporting Information [Line Items]
Revenues	6,854	9,548	17,443	20,150
Segment contribution	2,526	3,449	6,837	6,803
Total assets	32,268	32,290	32,268	32,290
Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Income/loss from discontinued operations	15	200	159	178
Total assets		11		11
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Segment contribution	(5,475)	(6,465)	(17,875)	(21,747)
Interest expense, net	(53)	(96)	(172)	(312)
Miscellaneous	(8)	(15)	(31)	17
Income taxes-current	19	(120)	(42)	(387)
Income taxes-deferred	(3)	(55)	(93)	(50)
Noncontrolling interest	22	11	31	31
Total assets	$ 13,728	$ 8,997	$ 13,728	$ 8,997