Annual report pursuant to Section 13 and 15(d)

Information Concerning Industry Segments and Major Customers (Narrative) (Details)

v3.10.0.1
Information Concerning Industry Segments and Major Customers (Narrative) (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2018
USD ($)
segment
customer
Dec. 31, 2017
USD ($)
customer
Segment Reporting Information [Line Items]    
Number of segments | segment 4  
Sales [Member] | Suttle [Member]    
Segment Reporting Information [Line Items]    
Number of customers 1 1
Sales [Member] | Transition Networks [Member]    
Segment Reporting Information [Line Items]    
Number of customers 1  
Accounts Receivable [Member] | Suttle [Member]    
Segment Reporting Information [Line Items]    
Number of customers 1 1
Accounts Receivable [Member] | Transition Networks [Member]    
Segment Reporting Information [Line Items]    
Number of customers   2
Foreign Countries [Member] | Suttle [Member]    
Segment Reporting Information [Line Items]    
Long-lived assets | $ $ 159 $ 93
United States [Member] | Sales [Member]    
Segment Reporting Information [Line Items]    
Concentration risk percentage 83.00% 83.00%
One Customer [Member] | Sales [Member] | Suttle [Member]    
Segment Reporting Information [Line Items]    
Concentration risk percentage 10.30% 10.30%
One Customer [Member] | Sales [Member] | Transition Networks [Member]    
Segment Reporting Information [Line Items]    
Concentration risk percentage 11.30%  
One Customer [Member] | Accounts Receivable [Member] | JDL Technologies [Member]    
Segment Reporting Information [Line Items]    
Concentration risk percentage 15.00%  
Number of customers 1  
One Customer [Member] | Accounts Receivable [Member] | Suttle [Member]    
Segment Reporting Information [Line Items]    
Concentration risk percentage 14.00% 21.00%
Two Customers [Member] | Accounts Receivable [Member] | Transition Networks [Member]    
Segment Reporting Information [Line Items]    
Number of customers 2  
Customer 1 [Member] | Accounts Receivable [Member] | Transition Networks [Member]    
Segment Reporting Information [Line Items]    
Concentration risk percentage 16.00% 17.00%
Customer 2 [Member] | Accounts Receivable [Member] | Transition Networks [Member]    
Segment Reporting Information [Line Items]    
Concentration risk percentage 14.00% 15.00%