v3.3.1.900
Summary of significant accounting policies (Details 4)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2015
USD ($)
item
$ / shares
shares
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Foreign Currency Translation      
Cumulative foreign currency translation adjustments, net of tax in accumulated other comprehensive income $ (1,160) $ (443)  
Income tax expense related to foreign currency translation adjustments 0 0  
Advertising, marketing and promotion costs      
Capitalized advertising production costs 0 0 $ 0
Advertising expenses $ 1,703 $ 1,350 $ 2,302
Assumptions that were used to calculate the grant date fair value of employee stock option grants      
Number of stock options granted | shares 0    
Dividends declared on common stock (in dollars per share) | $ / shares $ 0    
Dividends paid on common stock (in dollars per share) | $ / shares $ 0.00    
Number of dividend payouts anticipated in the foreseeable future | item 0    
Stock options      
Assumptions that were used to calculate the grant date fair value of employee stock option grants      
Expected term   6 years 3 months 6 years 3 months
Expected volatility (as a percent)   48.60% 49.31%
Risk-free interest rate (as a percent)   1.80% 1.34%
Dividend yield (as a percent)   0.00% 0.00%
DAS license agreements | Minimum      
Revenue recognition      
Term of the arrangement used to determine revenue recognition 5 years    
DAS license agreements | Maximum      
Revenue recognition      
Term of the arrangement used to determine revenue recognition 20 years    
Wholesale - Wi-Fi | Minimum      
Revenue recognition      
Term of the arrangement used to determine revenue recognition 1 year    
Wholesale - Wi-Fi | Maximum      
Revenue recognition      
Term of the arrangement used to determine revenue recognition 5 years