Note 4 - Revolving Line of Credit (Details Textual) - Revolving Credit Facility [Member] - Texas Capital Bank, National Association [Member] - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,500,000
Line of Credit Facility, Borrowing Base, Percent of Receivables	80.00%
Line of Credit Facility, Interest Rate at Period End	4.80%	5.37%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.25%
Line of Credit Facility, Minimum Liquidity Threshold	$ 500,000
Total Leverage Ratio, Maximum Threshold	3
Total Interest Coverage Ratio, Minimum Threshold	2.5
Total Fixed Charge Coverage Ratio, Minimum Threshold	1.25
Line of Credit Facility, Annual Draw Limit	$ 250,000
Long-term Line of Credit, Total	0	$ 0
Line of Credit Facility, Current Borrowing Capacity	$ 135,000	$ 100,000
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	3.00%