v3.26.1
Note 12 - Business Segment Information - Segment Information (Details) - USD ($)
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Revenue from Contract with Customer, Including Assessed Tax $ 1,248,000 $ 2,777,000 $ 2,363,000 $ 6,046,000  
Stock option expense 722,000 492,000 1,421,000 1,107,000  
Depreciation (31,000) (36,000) (67,000) (78,000)  
Research and development expense (1,088,000) (535,000) (1,995,000) (1,324,000)  
Operating income (loss) (3,728,000) (1,802,000) (6,931,000) (3,664,000)  
Interest income (expense) (272,000) (80,000) (389,000) (145,000)  
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (4,000,000) (1,882,000) (7,405,000) (3,803,000)  
Tangible assets 5,460,000   5,460,000   $ 6,945,000
Operating lease right-of use 927,000   927,000   1,028,000
Finance lease right-of-use 282,000   282,000   338,000
Total 6,669,000   6,669,000   8,311,000
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]          
Revenue from Contract with Customer, Including Assessed Tax 9,000 0 9,000 0  
Stock option expense 472,000 292,000 758,000 701,000  
Depreciation (10,000) (10,000) (19,000) (19,000)  
Research and development expense (323,000) (219,000) (584,000) (466,000)  
Operating income (loss) (889,000) (1,045,000) (1,338,000) (1,858,000)  
Interest income (expense) 1,000 3,000 64,000 6,000  
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (888,000) (1,042,000) (1,359,000) (1,853,000)  
Tangible assets 515,000   515,000   694,000
Operating lease right-of use 173,000   173,000   238,000
Finance lease right-of-use 0   0   0
Total 688,000   688,000   932,000
Operating Segments [Member] | Odor-No-More [Member]          
Revenue from Contract with Customer, Including Assessed Tax 471,000 2,006,000 895,000 4,809,000  
Depreciation (9,000) (10,000) (23,000) (23,000)  
Operating income (loss) (110,000) 823,000 (204,000) 1,780,000  
Interest income (expense) (3,000) 33,000 (3,000) 47,000  
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (113,000) 856,000 (207,000) 1,827,000  
Tangible assets 1,629,000   1,629,000   2,331,000
Operating lease right-of use 0   0   0
Finance lease right-of-use 0   0   0
Total 1,629,000   1,629,000   2,331,000
Operating Segments [Member] | Clyra Segment [Member]          
Revenue from Contract with Customer, Including Assessed Tax 0 0 154,000 0  
Stock option expense 250,000 200,000 663,000 406,000  
Depreciation (2,000) (3,000) (4,000) (4,000)  
Research and development expense (610,000) (229,000) (1,131,000) (564,000)  
Operating income (loss) (2,105,000) (1,263,000) (3,826,000) (2,580,000)  
Interest income (expense) (270,000) (116,000) (450,000) (198,000)  
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (2,375,000) (1,379,000) (4,275,000) (2,778,000)  
Tangible assets 2,113,000   2,113,000   2,650,000
Operating lease right-of use 162,000   162,000   175,000
Finance lease right-of-use 282,000   282,000   338,000
Total 2,557,000   2,557,000   3,163,000
Operating Segments [Member] | BioLargo Engineering, Science & Technologies, LLC [Member]          
Revenue from Contract with Customer, Including Assessed Tax 1,090,000 940,000 1,888,000 1,630,000  
Depreciation (8,000) (11,000) (17,000) (28,000)  
Research and development expense (255,000) (82,000) (463,000) (326,000)  
Operating income (loss) (45,000) 16,000 (426,000) (364,000)  
Tangible assets 1,248,000   1,248,000   1,169,000
Operating lease right-of use 592,000   592,000   615,000
Finance lease right-of-use 0   0   0
Total 1,840,000   1,840,000   1,784,000
Operating Segments [Member] | BioLargo Energy Technologies, Inc (BETI) [Member]          
Depreciation (2,000) (2,000) (4,000) (4,000)  
Research and development expense (156,000) (54,000) (298,000) (113,000)  
Operating income (loss) (339,000) (122,000) (694,000) (217,000)  
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (339,000) (122,000) (694,000) (217,000)  
Tangible assets 46,000   46,000   4,000
Operating lease right-of use 0   0   0
Finance lease right-of-use 0   0   0
Total 46,000   46,000   4,000
Operating Segments [Member] | BioLargo Canada [Member]          
Revenue from Contract with Customer, Including Assessed Tax 70,000 0 126,000 8,000  
Research and development expense (87,000) (120,000) (179,000) (256,000)  
Operating income (loss) (105,000) (144,000) (218,000) (300,000)  
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (105,000) (144,000) (219,000) (294,000)  
Tangible assets 112,000   112,000   321,000
Operating lease right-of use 0   0   0
Finance lease right-of-use 0   0   0
Total 112,000   112,000   321,000
Operating Segments [Member] | BioLargo Consumer Products Group (BCPG) [Member]          
Research and development expense (40,000) 0 (40,000) 0  
Operating income (loss) (60,000) 0 (60,000) 0  
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (60,000) 0 (60,000) 0  
Operating Segments [Member] | BEST [Member]          
Operating income (loss) (75,000) (67,000) (165,000) (125,000)  
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (75,000) (67,000) (165,000) (125,000)  
Operating Segments [Member] | BLEST [Member]          
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest (45,000) 16,000 (426,000) (363,000)  
Consolidation, Eliminations [Member]          
Revenue from Contract with Customer, Including Assessed Tax (392,000) (169,000) (709,000) (401,000)  
Research and development expense 383,000 $ 169,000 700,000 $ 401,000  
Tangible assets (203,000)   (203,000)   (224,000)
Operating lease right-of use 0   0   0
Finance lease right-of-use 0   0   0
Total $ (203,000)   $ (203,000)   $ (224,000)