Note 10 - Business Segment Information - Segment Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Revenues	$ 191,159	$ 164,456
Cost of products sold	(145,138)	(122,142)
Gross profit	46,021	42,314
Operating Expenses	51,923	32,349
Segment contribution	(5,902)	9,965
Operating Income	(5,902)	9,965
Other expenses, net	(2,496)	(1,664)
Income tax provision	2,447	(1,892)
Non-controlling interest	53	(97)
Non-controlling interest	53	(97)
Net income attributable to Ultralife	(5,898)	6,312
Total assets	216,912	220,451
Capital expenditures	3,872	1,932
Goodwill	45,376	45,006
Depreciation and amortization of intangible assets	5,499	4,157
Stock-based compensation	935	698
Battery & Energy Products Segment [Member]
Goodwill	33,883	33,513
Communications Systems Segment [Member]
Goodwill	11,493	11,493
Operating Segments [Member]
Operating Expenses	(27,088)	(22,126)
Segment contribution	18,933	20,188
Operating Income	18,933	20,188
Operating Segments [Member] | Battery & Energy Products Segment [Member]
Revenues	178,042	144,081
Cost of products sold	(135,402)	(107,764)
Gross profit	42,640	36,317
Operating Expenses	(22,417)	(17,320)
Segment contribution	20,223	18,997
Operating Income	20,223	18,997
Total assets	165,592	173,954
Capital expenditures	3,872	1,261
Goodwill	33,883	33,513
Depreciation and amortization of intangible assets	5,115	3,676
Stock-based compensation	602	383
Operating Segments [Member] | Communications Systems Segment [Member]
Revenues	13,117	20,375
Cost of products sold	(9,736)	(14,378)
Gross profit	3,381	5,997
Operating Expenses	(4,671)	(4,806)
Segment contribution	(1,290)	1,191
Operating Income	(1,290)	1,191
Total assets	27,201	26,876
Capital expenditures	0	513
Goodwill	11,493	11,493
Depreciation and amortization of intangible assets	231	237
Stock-based compensation	97	96
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Revenues	0	0
Cost of products sold	0	0
Gross profit	0	0
Operating Expenses	(24,835)	(10,223)
Other expenses, net	(2,496)	(1,664)
Income tax provision	2,447	(1,892)
Non-controlling interest	53	(97)
Non-controlling interest	53	(97)
Total assets	24,119	19,621
Capital expenditures	0	158
Goodwill	0	0
Depreciation and amortization of intangible assets	153	244
Stock-based compensation	$ 236	$ 219