Note 7 - Accounts Payable and Accrued Expenses - Summary of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Accounts payable	$ 1,663	$ 1,212
Accrued payroll	77	251
Total	1,740	1,488
Accrued interest		25
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Accounts payable	200	163
Accrued payroll	13	49
Accrued interest		25
Operating Segments [Member] | Odor-No-More [Member]
Accounts payable	1,357	964
Accrued payroll	39	86
Accrued interest		0
Operating Segments [Member] | BLEST [Member]
Accounts payable	62	34
Accrued payroll	22	116
Accrued interest		0
Operating Segments [Member] | BioLargo Canada [Member]
Accounts payable	44	93
Accrued payroll	0	0
Accrued interest		0
Operating Segments [Member] | BioLargo Energy Technologies, Inc (BETI) [Member]
Accounts payable	24	40
Accrued payroll	0	0
Accrued interest		0
Operating Segments [Member] | BEST [Member]
Accounts payable	0	0
Accrued payroll	3	0
Accrued interest		0
Consolidation, Eliminations [Member]
Accounts payable	(24)	(82)
Accrued payroll	$ 0	0
Accrued interest		$ 0