Note 7 - Accounts Payable and Accrued Expenses - Summary of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Accounts payable	$ 1,039	$ 717
Accrued payroll	160	198
Accrued interest	25	25
Total	1,224	940
Corporate, Non-Segment [Member]
Accounts payable	169	187
Accrued payroll	36	20
Accrued interest	25	25
Total
Operating Segments [Member] | Odor-No-More [Member]
Accounts payable	794	486
Accrued payroll	49	58
Accrued interest	0	0
Total
Operating Segments [Member] | BLEST [Member]
Accounts payable	37	7
Accrued payroll	75	120
Accrued interest	0	0
Total
Operating Segments [Member] | BioLargo Water [Member]
Accounts payable	121	119
Accrued payroll	0	0
Accrued interest	0	0
Total
Consolidation, Eliminations [Member]
Accounts payable	(82)	(82)
Accrued payroll	0	0
Accrued interest	0	0
Total