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Employee Benefit Plans and Stock-Based Compensation - Assumptions (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Weighted-average assumptions [Abstract]      
Expected term 0 years 6 years 1 month 6 days 5 years 9 months 18 days
Volatility (in hundredths)   49.50% 46.60%
Expected dividend (in hundredths) 0.00% 0.00% 0.00%
Risk-free interest rate (in hundredths)   1.67% 3.09%
Retirement Savings Plan [Abstract]      
Period after which all full time employees are eligible to participate in the savings plan 90 days    
Contributions to the retirement savings plans $ 188,000 $ 176,000 $ 180,000
Maximum      
Retirement Savings Plan [Abstract]      
Maximum percentage of employer matching contribution if employees contribute at least 6% of base pay (in hundredths) 4.00%    
Minimum      
Retirement Savings Plan [Abstract]      
Minimum percentage of employee contribution to get 4% of employer's contribution (in hundredths) 6.00%