Note 7 - Accounts Payable and Accrued Expenses - Summary of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounts payable	$ 717	$ 350
Accrued payroll	198	184
Accrued interest	25	25
Total	940	559
Corporate, Non-Segment [Member]
Accounts payable	187	156
Accrued payroll	20	37
Accrued interest	25	25
Total
Operating Segments [Member] | Odor-No-More [Member]
Accounts payable	486	72
Accrued payroll	58	53
Accrued interest	0	0
Total
Operating Segments [Member] | BLEST [Member]
Accounts payable	7	73
Accrued payroll	120	94
Accrued interest	0	0
Total
Operating Segments [Member] | BioLargo Water [Member]
Accounts payable	119	96
Accrued payroll	0	0
Accrued interest	0	0
Total
Consolidation, Eliminations [Member]
Accounts payable	(82)	(47)
Accrued payroll	0	0
Accrued interest	0	0
Total