Note 18 - Concentrations - Concentration Risk (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Concentration risk, percentage	100.00%	100.00%
UNITED KINGDOM
Concentration risk, percentage	15.00%	15.00%
Revenue Benchmark [Member] | Power and Electromechanical Segment [Member]
Concentration risk, percentage	76.00%	77.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration risk, percentage	28.00%	37.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration risk, percentage	0.00%	0.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration risk, percentage	15.00%	15.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | UNITED KINGDOM
Concentration risk, percentage	15.00%	15.00%
Geographic Concentration Risk [Member] | Accounts Receivable [Member]
Concentration risk, percentage	22.00%		29.00%
Geographic Concentration Risk [Member] | Accounts Receivable [Member] | UNITED KINGDOM
Concentration risk, percentage	22.00%		29.00%
Digi Key Electronics [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Power and Electromechanical Segment [Member]
Concentration risk, percentage	18.00%	25.00%
Future Electronics [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Power and Electromechanical Segment [Member]
Concentration risk, percentage	10.00%	12.00%