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Fair Value Measurements - Financial Instruments Measured on a Recurring Basis (Details)
3 Months Ended
Mar. 31, 2021
USD ($)
$ / shares
Phantom Stock Units  
Financial instruments measured at fair value on a recurring basis  
Expected dividends | $ $ 0
Minimum | Phantom Stock Units  
Financial instruments measured at fair value on a recurring basis  
Grant date fair value (in dollars per share) | $ / shares $ 1.70
Risk-free interest rate 0.27%
Expected life (years) 2 years 8 months 15 days
Estimated volatility factor (percent) 65.10%
Maximum | Phantom Stock Units  
Financial instruments measured at fair value on a recurring basis  
Grant date fair value (in dollars per share) | $ / shares $ 7.28
Risk-free interest rate 2.39%
Expected life (years) 2 years 9 months
Estimated volatility factor (percent) 69.90%
Liability-classified stock compensation | Recurring | Level 3  
Financial instruments measured at fair value on a recurring basis  
Fair value of liability | $ $ 315,000