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Stock Benefit Plans and Stock-Based Compensation (Tables) | 12 Months Ended
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Dec. 31, 2022
Share-Based Payment Arrangement [Abstract] |
Summary of Compensation Cost for Stock-Based Compensation Arrangements | The compensation cost that has been included in the Company’s consolidated statements of operations for all stock-based compensation arrangements is detailed as follows (in thousands):
|  | Year Ended December 31, |
|  | 2022 |  |  | 2021 |  |  | 2020 |
Cost of sales |  | $ | 2,597 |  |  | $ | 737 |  |  | $ | 512 |
Research and development |  |  | 5,016 |  |  |  | 4,056 |  |  |  | 2,114 |
Sales, general and administrative |  |  | 32,943 |  |  |  | 31,657 |  |  |  | 15,033 |
Total |  | $ | 40,556 |  |  | $ | 36,450 |  |  | $ | 17,659 |
Summary of Stock Option Activity | A summary of the Company’s stock option activity under the Plans and related information is as follows (in thousands, except as indicated and per share data):
|  | Shares |  |  | Weighted average exercise price |  |  | Weighted average remaining contractual term (in years) |  |  | Aggregate intrinsic value |
Outstanding at December 31, 2021 |  |  | 3,351 |  |  | $ | 3.50 |  |  |  |  |  |  |
Exercised |  |  | (378 | ) |  |  | 2.84 |  |  |  |  |  |  |
Forfeited |  |  | (57 | ) |  |  | 13.83 |  |  |  |  |  |  |
Outstanding at December 31, 2022 |  |  | 2,916 |  |  | $ | 3.38 |  |  |  | 4.58 |  |  | $ | 26,783 |
Options vested and expected to vest at December 31, 2022 |  |  | 2,916 |  |  | $ | 3.38 |  |  |  | 4.58 |  |  | $ | 26,783 |
Options exercisable at December 31, 2022 |  |  | 2,849 |  |  | $ | 3.22 |  |  |  | 4.51 |  |  | $ | 26,550 |
Summary of Weighted Average Assumptions Used to Compute Stock-Based Compensation Costs for Stock Options Granted | The weighted average assumptions used to compute the stock-based compensation costs for the stock options granted during the years ended December 31, 2021 and 2020 are as follows:
| Year Ended December 31, |
|  | 2021 |  |  | 2020 |
Risk-free interest rate |  |  | 0.84 | % |  |  | 1.03 | %
Expected dividend yield |  |  | — |  |  |  | — |
Weighted average expected life (years) |  |  | 6.07 |  |  |  | 6.08 |
Volatility |  |  | 87.38 | % |  |  | 84.00 | %
Summary of Information about Restricted Stock Awards, Restricted Stock Units and Performance-Based Restricted Units Activity | The following table summarizes information about the restricted stock units and performance-based restricted units activity (in thousands, except as indicated and per share data):
|  | Shares |  |  | Weighted average grant date fair value |  |  | Weighted average remaining recognition period (in years) |
Unvested at December 31, 2021 |  |  | 8,703 |  |  | $ | 6.34 |  |  |  |
Awarded |  |  | 3,909 |  |  |  | 8.13 |  |  |  |
Vested |  |  | (3,316 | ) |  |  | 4.68 |  |  |  |
Forfeited |  |  | (763 | ) |  |  | 6.30 |  |  |  |
Unvested at December 31, 2022 |  |  | 8,533 |  |  | $ | 6.63 |  |  |  | 1.43 |
Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Stock Purchase Rights under ESPP | The Company estimates the fair value of shares issued to employees under the ESPP using the Black-Scholes option-pricing model. The assumptions used to estimate the fair value of stock purchase rights under the ESPP are as follows:
|  | Year Ended December 31, |
|  | 2022 |  |  | 2021 |  |  | 2020 |
Risk-free interest rate |  | 0.07% - 4.54% |  |  | 0.04% - 0.12% |  |  | 0.12% - 1.58% |
Expected dividend yield |  |  | — |  |  |  | — |  |  |  | — |
Expected term (years) |  | 0.50 - 0.60 |  |  |  | 0.50 |  |  |  | 0.50 |
Volatility |  | 50.29% - 64.53% |  |  | 49.98% - 78.37% |  |  | 54.96% - 102.5% |
Summary of Common Stock Reserved for Future Issuance | Common stock reserved for future issuance consists of the following (in thousands):
|  | December 31, 2022 |
Stock options outstanding |  |  | 2,916 |
Unvested restricted stock units |  |  | 8,533 |
Employee stock purchase plan |  |  | 119 |
Senior convertible notes |  |  | 17,246 |
Warrants outstanding |  |  | 15,491 |
Authorized for future grant under the Distributor and Development Services plans |  |  | 281 |
Authorized for future grant under the Management Objective Strategic Incentive Plan |  |  | 274 |
Authorized for future grant under the Company Equity plans |  |  | 1,269 |
|  |  | 46,129 |

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