Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	[1]	May 31, 2017	Nov. 30, 2010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)			11,300		11,300
Letters of Credit Outstanding, Amount		$ 0			$ 0
Accounts Receivable, Allowance for Credit Loss, Current		391			391		$ 335
Amortization of Intangible Assets, Total		47			98
Impairment of Long-Lived Assets to be Disposed of					$ 0	$ 0
Share-based Payment Arrangement, Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)					9,002
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Expense		36		$ 38	$ 75	$ 191
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total		$ 292			$ 292
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)					2 years 251 days
Stock Incentive Plan 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)									400,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares)	50,000
Equity Appreciation Rights Plan 2010 [Member] | Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)										1,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)					0	137,500

[1] The balance sheet at December 31, 2019 has been derived from the audited financial statements at that date