v3.10.0.1
Summary of significant accounting policies - Adoption of ASC 606 (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Jan. 01, 2018
Dec. 31, 2017
Adoption of ASC 606            
Accumulated deficit $ (129,824)   $ (129,824)     $ (131,967)
Accounts receivable, net 37,444   37,444   $ 25,079 26,148
Prepaid expenses and other current assets 7,200   7,200   6,539 6,369
Other assets 7,771   7,771   7,903 10,082
Deferred revenue, current 67,446   67,446   75,884 61,708
Deferred revenue, net of current portion 135,450   135,450   128,588 149,168
Non-controlling interests 1,572   1,572     1,212
Revenue 59,601 $ 49,033 117,760 $ 93,366    
Income tax expense 16 141 144 340    
Non-controlling interests 395 $ 160 851 $ 267    
Adjustment for adoption            
Adoption of ASC 606            
Accounts receivable, net         (1,069)  
Prepaid expenses and other current assets         170  
Other assets         (2,179)  
Deferred revenue, current         14,176  
Deferred revenue, net of current portion         (20,580)  
ASC 606 | As per ASC 605            
Adoption of ASC 606            
Accounts receivable, net 37,955   37,955     26,148
Prepaid expenses and other current assets 7,177   7,177     6,369
Other assets 9,948   9,948     10,082
Deferred revenue, current 67,128   67,128     61,708
Deferred revenue, net of current portion 147,468   147,468     $ 149,168
Non-controlling interests (54)   (54)      
Revenue 58,394   112,284      
Income tax expense 129   380      
Non-controlling interests 132   (707)      
ASC 606 | Adjustment for adoption            
Adoption of ASC 606            
Accumulated deficit         3,257  
Accounts receivable, net (511)   (511)      
Prepaid expenses and other current assets 23   23      
Other assets (2,177)   (2,177)      
Deferred revenue, current 318   318      
Deferred revenue, net of current portion (12,018)   (12,018)      
Non-controlling interests 1,626   1,626   $ 69  
Revenue 1,207   5,476      
Income tax expense (113)   (236)      
Non-controlling interests $ 263   $ 1,558