v3.8.0.1
Summary of significant accounting policies - Principles of consolidation (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Jan. 01, 2016
Accounting Standards Update 2016-09 [Member] | Early adoption    
Basis of presentation    
Increase to additional paid-in capital and accumulated deficit due to cumulative effect of a change in accounting principle   $ 94
Accounting Standards Update 2016-09 [Member] | Early adoption | Federal    
Basis of presentation    
Increase to deferred tax assets   6,933
Accounting Standards Update 2016-09 [Member] | Early adoption | State    
Basis of presentation    
Increase to deferred tax assets   $ 589
Chicago Concourse Development Group, LLC    
Principles of consolidation    
Percentage of ownership in subsidiaries 70.00%  
Boingo Holding Participacoes Ltda.    
Principles of consolidation    
Percentage of ownership in subsidiaries 75.00%