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v3.21.2

Stockholders' Equity (Schedule of Fair Value of Employee Stock Options) (Details) - $ / shares | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Expected volatility | 67.00% | 71.00% |  |
Weighted average grant date fair value per share | $ 5.97 | $ 3.85 | $ 15.63 | $ 3.82
Options to purchase common stock [Member] |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Expected term in years |  | 5 years 1 month 6 days |  | 5 years 1 month 6 days
Expected volatility |  | 71.00% |  |
Risk-free interest rate |  | 0.30% |  |
Options to purchase common stock [Member] | Minimum [Member] |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Expected term in years | 2 years 1 month 6 days |  | 2 years 1 month 6 days |
Expected volatility | 67.00% |  | 67.00% | 57.00%
Risk-free interest rate, minimum | 0.05% |  | 0.05% | 0.30%
Options to purchase common stock [Member] | Maximum [Member] |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Expected term in years | 4 years 7 months 6 days |  | 4 years 7 months 6 days |
Expected volatility | 80.00% |  | 80.00% | 71.00%
Risk-free interest rate, maximum | 0.71% |  | 0.74% | 1.20%

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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The maximum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
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- Definition The minimum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
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- Definition Rate of weighted-average expected volatility for award under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.D.2) -URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809 + Details
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