Annual report pursuant to Section 13 and 15(d)

Stock-based Plans and Stock-based Compensation (Valuation Assumptions) (Details)

v3.21.1
Stock-based Plans and Stock-based Compensation (Valuation Assumptions) (Details)
12 Months Ended
Dec. 17, 2020
Dec. 07, 2020
Nov. 05, 2020
Apr. 06, 2020
Mar. 24, 2020
Nov. 19, 2019
Oct. 21, 2019
Aug. 21, 2019
May 17, 2019
Mar. 11, 2019
Feb. 25, 2019
Feb. 18, 2019
Feb. 12, 2019
Jan. 21, 2019
Jan. 07, 2019
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Expected life (years)                               6 years 6 years 22 days
Expected dividend yield                               0.00% 0.00%
Expected volatility 77.41% 77.35% 77.36% 78.21% 77.56% 78.70% 74.18% 80.17% 80.17% 90.90% 90.88% 90.88% 90.79% 90.75% 90.82%    
Minimum [Member]                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Risk-free interest rate                               0.42% 1.49%
Expected volatility                               77.36% 74.18%
Maximum [Member]                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Risk-free interest rate                               0.58% 2.65%
Expected volatility                               78.21% 90.90%