Note 8 - Noncontrolling Interest - Clyra Medical (Details Textual)			1 Months Ended			3 Months Ended						9 Months Ended		12 Months Ended
	Dec. 15, 2023	Jun. 30, 2020 USD ($) shares	Jul. 31, 2024 USD ($) shares	Jun. 30, 2024 USD ($) shares	Jan. 31, 2023 shares	Sep. 30, 2024 USD ($) $ / shares shares	Jun. 30, 2024 USD ($) shares	Mar. 31, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) shares	Apr. 08, 2022 USD ($)
Debt Conversion, Original Debt, Amount												$ 84,000	$ 1,860,000
Long-Term Line of Credit						$ 134,000						134,000
Line of Credit Facility, Interest Rate During Period						15.00%
Stock Issued During Period, Value, New Issues						$ 15,000	$ 136,000	$ 488,000	$ 203,000	$ 494,000	$ 800,000
Research and Development Expense						$ 690,000			694,000			$ 2,098,000	1,846,000
Common Stock, Shares, Issued (in shares) | shares						301,163,538						301,163,538		292,945,747
Warrants and Rights Outstanding						$ 0						$ 0
Share Price (in dollars per share) | $ / shares						$ 0.23						$ 0.23
Share-Based Payment Arrangement, Option [Member]
Share-Based Payment Arrangement, Expense						$ 43,000			$ 45,000			$ 165,000	$ 172,000
Clyra Medical [Member] | Common Stock [Member]
Investment Owned, Balance, Shares (in shares) | shares						5,471,156						5,471,156		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						2,730	2,730	27,600					0
Stock Issued During Period, Value, New Issues						$ 37,000	$ 14,000
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						10,452,377						10,452,377		10,000,749
Common Stock, Shares, Issued (in shares) | shares						297,397						297,397
Preferred Stock Dividends and Other Adjustments												$ 503,000		$ 241,000
Clyra Medical [Member] | Share-Based Payment Arrangement, Option [Member] | Employees and Consultants [Member]
Share-Based Payment Arrangement, Expense												$ 131,000	$ 172,000
Share Price (in dollars per share) | $ / shares						$ 4.5			$ 2.71			$ 4.5	$ 2.71
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount Rate												30.00%
Clyra Medical [Member] | Vendors [Member]
Proceeds from Issuance or Sale of Equity												$ 1,290,000
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						146,083						146,083
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares						$ 7.5						$ 7.5
Number of Accredited Investors						5						5
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						$ 3.72
Warrants and Rights Outstanding						$ 524,000						$ 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						146,083						146,083
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares						$ 7.5						$ 7.5
Warrants and Rights Outstanding						$ 156,000						$ 156,000
Share Price (in dollars per share) | $ / shares						$ 4.5			$ 2.71			$ 4.5	$ 2.71
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount Rate												30.00%
Warrants and Rights Outstanding, Term (Year)						3 years						3 years
Clyra Medical [Member] | Series A Preferred Stock [Member]
Shares Issued, Price Per Share (in dollars per share) | $ / shares						$ 3.1						$ 3.1
Shares, Outstanding (in shares) | shares						746,418						746,418		746,418
Preferred Stock, Dividend Rate, Percentage												15.00%
Preferred Stock, Convertible, Sale of Stock Amount						$ 5,000,000						$ 5,000,000
Clyra Medical [Member] | Preferred Class A [Member]
Stock Issued During Period, Shares, New Issues (in shares) | shares												746,618
Proceeds from Issuance of Preferred Stock and Preference Stock												$ 1,800,000
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] | Shares Issued For Conversion of Notes Payable [Member]
Debt Conversion, Original Debt, Amount			$ 119,000
Debt Conversion, Converted Instrument, Shares Issued (in shares) | shares			34,126
Clyra Medical [Member] | Preferred Shares Issued for Debt Owed to Biolargo [Member]
Debt Conversion, Converted Instrument, Shares Issued (in shares) | shares				148,156
Debt Conversion, Converted Instrument, Amount				$ 741,000
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%
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