Quarterly report pursuant to Section 13 or 15(d)

Concentrations (Details)

v3.8.0.1
Concentrations (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Concentration Risk [Line Items]      
Cash and cash equivalents $ 168,931   $ 48,260
Sales Revenue Segment | Customer Concentration Risk      
Concentration Risk [Line Items]      
Southwest Airlines, concentration risk, percent 18.00% 18.00%  
Sales Revenue Segment | Customer Concentration Risk | Connectivity      
Concentration Risk [Line Items]      
Southwest Airlines, concentration risk, percent 33.00% 36.00%  
Accounts Receivable | Customer Concentration Risk      
Concentration Risk [Line Items]      
Southwest Airlines, concentration risk, percent 9.00%   10.00%
Foreign Subsidiaries      
Concentration Risk [Line Items]      
Cash and cash equivalents $ 21,100