Note 3 - Debt (Details Textual) - Revolving Credit Facility [Member] - Wells Fargo [Member]	12 Months Ended
	Dec. 31, 2017 USD ($)
Line of Credit Facility, Maximum Borrowing Capacity	$ 6,000,000
Line of Credit Facility, Excess Availability Requirement	2,000,000
Line of Credit Facility, Current Borrowing Capacity	$ 4,000,000
Line of Credit Facility, Covenant, Minimum Fixed Charge Ratio	1.1
Line of Credit Facility, Covenant Term	1 year
Long-term Line of Credit	$ 0
Line of Credit Facility, Covenant Compliance, Maximum Outstanding Amount	$ 250,000
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	3.50%