Note 5 - Stock-based Compensation; Changes in Equity (Details Textual) - USD ($)								3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 05, 2020	Jun. 01, 2020	Apr. 13, 2020	Apr. 01, 2020	Feb. 21, 2020	Jan. 30, 2020	Jan. 03, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 26, 2020	Dec. 31, 2019	Feb. 24, 2020	Jun. 08, 2018	Apr. 10, 2009
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate										0.00%		0.00%
Share-based Payment Arrangement, Expense								$ 0	$ 29,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total								$ 0	$ 29,000	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)								812,285		812,285		471,144
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value								$ 0		$ 0
LF International [Member] | Yunhong CTI [Member]
Ownership Percentage	57.00%
Conversion to an Accounts Receivable [Member]
Debt Conversion, Original Debt, Amount										478,000
Series A Preferred Stock [Member]
Preferred Stock Redemption Premium	$ 2,500,000
Preferred Stock, Dividend Rate, Percentage	8.00%
Preferred Stock, Dividend Rate, Per-Dollar-Amount (in dollars per share)	$ 10
Dividends, Total										$ 150,000
Series A Preferred Stock [Member] | Conversion to an Accounts Receivable [Member]
Debt Conversion, Original Debt, Amount				$ 482,000
Accounts Receivable, Shares Converted to Preferred Stock (in shares)				48,200
Purchase Agreement [Member]
Stock Issued During Period, Shares, New Issues (in shares)											400,000
Purchase Agreement [Member] | Series A Preferred Stock [Member]
Sale of Stock, Shares Agreed to Purchase (in shares)							500,000
Shares Issued, Price Per Share (in dollars per share)							$ 10
Sale of Stock, Offering Amount							$ 5,000,000
Accounts Receivable, Shares Converted to Preferred Stock (in shares)		48,200
Second Purchase Agreement Amendment [Member] | Series A Preferred Stock [Member]
Sale of Stock, Shares Agreed to Purchase (in shares)			130,000
Shares Issued, Price Per Share (in dollars per share)	$ 10		$ 10
Proceeds from Issuance of Preferred Stock and Preference Stock	$ 500,000		$ 5,000,000
Sale of Stock, Contingent Additional Offered Shares (in shares)			260,000
Stock Issued During Period, Shares, New Issues (in shares)	50,000
Sale of Stock, Offering Amount			$ 1,300,000
Second Purchase Agreement Amendment [Member] | Series A Preferred Stock [Member] | Conversion from Each Share Series A Preferred Stock to Common Stock [Member]
Conversion of Stock, Shares Converted (in shares)							10
Additional Offering [Member] | Series A Preferred Stock [Member]
Sale of Stock, Contingent Additional Offered Shares (in shares)							200,000
Additional Shares Offering [Member] | Series A Preferred Stock [Member]
Sale of Stock, Price Per Share (in dollars per share)							$ 10
First Closing of the Offering [Member] | Series A Preferred Stock [Member]
Proceeds from Issuance of Preferred Stock and Preference Stock							$ 2,500,000
Stock Issued During Period, Shares, New Issues (in shares)							250,000
Purchase Agreement Amendment [Member] | Series A Preferred Stock [Member]
Sale of Stock, Shares Agreed to Purchase (in shares)													70,000
Shares Issued, Price Per Share (in dollars per share)													$ 10
Proceeds from Issuance of Preferred Stock and Preference Stock					$ 220,600	$ 206,000
Sale of Stock, Contingent Additional Offered Shares (in shares)													140,000
Stock Issued During Period, Shares, New Issues (in shares)					22,060	20,600
Sale of Stock, Offering Amount													$ 700,000
Second Closing of the Offering [Member] | Series A Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)					250,000
Stock Incentive Plan 2009 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)															510,000
Stock Incentive Plan 2018 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)														300,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)								20,000		20,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate										0.42%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate										153.73%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate										1.65%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate										161.48%