Net Loss per Share - Anti-Dilutive Securities (Details) - shares
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Outstanding options      
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect      
Anti dilutive securities were excluded from the calculation of diluted net loss per share 6,354,308 6,664,173 5,643,410