Note 10 - Significant Risk Concentrations (Details Textual) - USD ($)	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer, Excluding Assessed Tax, Total	$ 10,646,000	$ 10,420,000	$ 14,718,000	$ 31,289,000	$ 36,073,000	$ 43,994,000		$ 59,360,000
Accounts Receivable, after Allowance for Credit Loss, Current, Total	5,992,000			5,992,000			$ 6,177,000
GES Singapore Pte, LTD [Member]
Revenue from Contract with Customer, Excluding Assessed Tax, Total	1,100,000
Accounts Receivable, after Allowance for Credit Loss, Current, Total	$ 958,000			$ 958,000
GES Singapore Pte, LTD [Member] | Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk, Percentage	11.00%
GES Singapore Pte, LTD [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk, Percentage				16.00%
Honeywell International, Inc [Member]
Accounts Receivable, after Allowance for Credit Loss, Current, Total							$ 680,000
Honeywell International, Inc [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk, Percentage							12.00%
Kodak Alaris, Inc [Member]
Accounts Receivable, after Allowance for Credit Loss, Current, Total							$ 866,000
Kodak Alaris, Inc [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk, Percentage							15.00%