Annual report pursuant to Section 13 and 15(d)

Share-based compensation - Fair value assumptions (Details)

v3.21.1
Share-based compensation - Fair value assumptions (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rate, minimum 0.33% 1.49%
Risk-free interest rate, maximum 0.89% 2.39%
Expected volatility 67.50% 63.00%
Expected dividend yield 0.00% 0.00%
Minimum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected life 3 years 3 years
Maximum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected life 6 years 6 months 6 years 6 months