v3.10.0.1
Subsequent events (Details) - Subsequent events - Convertible Senior Notes
$ / shares in Units, $ in Thousands
1 Months Ended
Oct. 31, 2018
USD ($)
D
$ / shares
$ / EquityInstruments
Oct. 02, 2018
$ / shares
Subsequent events    
Gross proceeds from convertible senior notes | $ $ 201,250  
Percentage of interest rate per annum 1.00%  
Conversion ratio 0.0236323  
Conversion price per share | $ / shares $ 42.31  
Effective conversion price, percentage of premium to share closing price 30.00%  
Share price | $ / shares   $ 32.55
Percentage of redemption price 100.00%  
Threshold percentage of stock price trigger 130.00%  
Threshold trading days | D 20  
Threshold consecutive trading days | D 30  
Call option    
Subsequent events    
Derivative cap price (in dollars per share) | $ / EquityInstruments 65.10  
Derivative cap price, minimum percentage of premium on share price 100.00%  
Payment of derivative capped transactions | $ $ 23,967