Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	May 31, 2021	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020		May 31, 2017	Nov. 30, 2010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)					27,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)			214,391	45,326	144,892	21,220
Accounts Receivable, Allowance for Credit Loss, Current			$ 361		$ 361		$ 343	[1]
Employee Retention Credit			5,209		5,209
Assets Disposed of by Method Other than Sale, in Period of Disposition, Gain (Loss) on Disposition			$ (560)	$ (0)	(560)	$ (0)
Finite-Lived Intangible Assets, Remaining Amortization Period (Year)			3 years
Amortization of Intangible Assets, Total			$ 45		139		$ 185
Employee-related Liabilities, Current [Member]
Accrual for Taxes Other than Income Taxes			1,158		1,158
Cost of Sales [Member]
Employee Retention Credit			4,670		4,670
Selling Expense [Member]
Employee Retention Credit			125		125
General and Administrative Expense [Member]
Employee Retention Credit			414		414
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Expense			28	36	74	111
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total			320		$ 320
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)					3 years 1 month 13 days
Stock Appreciation Rights (SARs) [Member]
Share-based Payment Arrangement, Expense			13	$ 40	$ 127	$ 40
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)					0	0
Deferred Compensation Liability, Current, Total			$ 235		$ 235
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)	75,000	50,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)					27,000	11,300
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

[1] The balance sheet at December 31, 2020 has been derived from the audited financial statements at that date