Note 8 - Noncontrolling Interest - Clyra Medical (Details Textual)			1 Months Ended		3 Months Ended
	Dec. 15, 2023	Jun. 30, 2020 USD ($) shares	Jul. 31, 2023 USD ($) shares	Jan. 31, 2023 shares	Mar. 31, 2024 USD ($) $ / shares shares	Mar. 31, 2023 USD ($) $ / shares shares		Dec. 31, 2023 USD ($) shares	Apr. 08, 2022 USD ($)
Long-Term Line of Credit					$ 134,000			$ 134,000
Research and Development Expense					$ 784,000	$ 565,000
Preferred Stock, Shares Outstanding (in shares) | shares					0			0
Common Stock, Shares, Issued (in shares) | shares					295,801,370			292,945,747
Proceeds from Issuance of Preferred Stock and Preference Stock					$ 0	225,000
Warrants and Rights Outstanding					$ 4,021,000	$ 122,000	[1]
Share Price (in dollars per share) | $ / shares					$ 0.35
Clyra Medical [Member] | Common Stock [Member]
Investment Owned, Balance, Shares (in shares) | shares					5,322,775			5,322,775
Clyra Medical [Member] | Preferred Stock, Series A [Member]
Investment Owned, Balance, Shares (in shares) | shares					165,765			165,765
Clyra Medical [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	100
Stock Issued During Period, Shares, New Issues (in shares) | shares					27,600	0
Shares Issued, Price Per Share (in dollars per share) | $ / shares					$ 2.71
Research and Development Expense					$ 52,000
Stock Issued, Discount on Fair Value, Percentage					30.00%
Shares, Outstanding (in shares) | shares					10,095,749
Common Stock, Shares, Outstanding (in shares) | shares								10,000,749
Common Stock, Shares, Issued (in shares) | shares					95,000
Preferred Stock Dividends and Other Adjustments					$ 327,000	$ 241,000
Clyra Medical [Member] | Share-Based Payment Arrangement, Option [Member] | Employees and Consultants [Member]
Share-Based Payment Arrangement, Expense					$ 59,000	$ 61,000
Share Price (in dollars per share) | $ / shares					$ 4.5	$ 2.71
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount Rate					30.00%
Clyra Medical [Member] | Warrants Expiring February 28, 2027 [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares					47,500
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares					$ 7.5
Number of Accredited Investors					5
Proceeds from Issuance or Sale of Equity					$ 475,000
Clyra Medical [Member] | Warrants Issued in Conjunction With the Sale of Series A Preferred Stock [Member]
Shares Issued, Price Per Share (in dollars per share) | $ / shares					$ 3.72
Warrants and Rights Outstanding, Term (Year)					3 years
Warrants and Rights Outstanding					$ 524,000
Clyra Medical [Member] | Clyra Unit Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares					47,500
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares					$ 7.5
Warrants and Rights Outstanding, Term (Year)					3 years
Warrants and Rights Outstanding					$ 57,000
Clyra Medical [Member] | Preferred Shares Issued for Debt Owed to Biolargo [Member]
Debt Conversion, Converted Instrument, Amount			$ 96,000
Debt Conversion, Converted Instrument, Shares Issued (in shares) | shares			30,833
Clyra Medical [Member] | Preferred Class A [Member]
Stock Issued During Period, Shares, New Issues (in shares) | shares					746,618
Preferred Stock, Shares Outstanding (in shares) | shares					746,418
Proceeds from Issuance of Preferred Stock and Preference Stock					$ 1,800,000
Clyra Medical [Member] | Series A Preferred Stock [Member]
Shares Issued, Price Per Share (in dollars per share) | $ / shares					$ 3.1
Preferred Stock, Shares Outstanding (in shares) | shares								746,418
Preferred Stock, Dividend Rate, Percentage					15.00%
Preferred Stock, Convertible, Sale of Stock Amount					$ 5,000,000
Clyra Medical [Member] | Revolving Credit Facility [Member] | Vernal Bay Capital Group, LLC [Member] | Inventory Line of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,000,000
Proceeds from Lines of Credit, Total		$ 260,000
Repayments of Lines of Credit					126,000
Stock Issued During Period, Shares, Commitment Fee (in shares) | shares		32,200
Stock Issued During Period, Value, Commitment Fee		$ 70,000
Debt Instrument, Percentage of Principal Payment, Cap								15.00%
Clyra Medical [Member] | Notes Payable, Other Payables [Member]
Debt Instrument, Face Amount									$ 100,000
Debt Instrument, Interest Rate, Stated Percentage									8.00%
Debt Instrument, Convertible, Sale of Stock Amount									$ 5,000,000
Debt Instrument, Convertible, Conversion Percentage									70.00%
Debt Instrument, Outstanding Balance					$ 100,000			$ 100,000
Vernal Bay Capital Group, LLC [Member] | Conversion of Clyra Medical Stock Into Biolargo Common Stock [Member]
Stock Issued During Period, Shares, Commitment Fee (in shares) | shares				32,200
Conversion of Stock, Shares Issued (in shares) | shares				527,983

[1] Aggregate intrinsic value based on closing common stock price of $0.35 at March 31, 2024.