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Stock-Based Compensation (Tables)
6 Months Ended
Jun. 30, 2021
Share-based Payment Arrangement [Abstract]  
Schedule of Weighted Average Assumptions
The weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below:
 Three Months Ended June 30,Six Months Ended June 30,
 2021202020212020
Risk-free interest rate0.99%0.40%0.90%0.67%
Expected volatility93%80%92%77%
Expected life in years5.75.95.85.9
Dividend yield