Note 10 - Segment Information, Significant Customers, Industry Concentration and Geographic Areas (Details Textual) - Customer Concentration Risk [Member] - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Sales [Member] | Five Largest Customers [Member]
Concentration Risk, Percentage	40.00%	42.00%	41.00%
Sales [Member] | General Motors Company [Member]
Concentration Risk, Percentage	19.00%	13.00%	18.00%
Sales [Member] | Fiat Chrysler Automobiles [Member]
Concentration Risk, Percentage	9.00%	16.00%	10.00%
Sales [Member] | Ford Motor Company [Member]
Concentration Risk, Percentage	7.00%	8.00%	9.00%
Revenue Provided to the Automobile Manufacturing Industry [Member]
Concentration Risk, Percentage	40.00%	46.00%	46.00%
Accounts Receivable [Member]
Accounts Receivable, before Allowance for Credit Loss, Current	$ 31,327,000	$ 30,848,000