Quarterly report pursuant to Section 13 or 15(d)

Concentrations (Details)

v3.10.0.1
Concentrations (Details) - USD ($)
$ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Concentration Risk [Line Items]      
Cash and cash equivalents $ 31,731   $ 48,260
Sales Revenue Segment | Customer Concentration Risk      
Concentration Risk [Line Items]      
Southwest Airlines, concentration risk, percent 18.00% 19.00%  
Sales Revenue Segment | Customer Concentration Risk | Connectivity      
Concentration Risk [Line Items]      
Southwest Airlines, concentration risk, percent 34.00% 36.00%  
Accounts Receivable | Customer Concentration Risk      
Concentration Risk [Line Items]      
Southwest Airlines, concentration risk, percent 13.00%   10.00%
Foreign Subsidiaries      
Concentration Risk [Line Items]      
Cash and cash equivalents $ 20,200