Note 7 - Accounts Payable and Accrued Expenses - Summary of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Accounts payable	$ 789	$ 826
Accrued payroll	102	120
Total	891	946
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Accounts payable	315	221
Accrued payroll	9	12
Operating Segments [Member] | Odor-No-More [Member]
Accounts payable	341	511
Accrued payroll	83	68
Operating Segments [Member] | BLEST [Member]
Accounts payable	87	73
Accrued payroll	2	40
Operating Segments [Member] | BioLargo Canada [Member]
Accounts payable	49	24
Accrued payroll	0	0
Operating Segments [Member] | BioLargo Energy Technologies, Inc (BETI) [Member]
Accounts payable	0	31
Accrued payroll	0	0
Operating Segments [Member] | BEST [Member]
Accounts payable	0	0
Accrued payroll	8	0
Consolidation, Eliminations [Member]
Accounts payable	(3)	(34)
Accrued payroll	$ 0	$ 0