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STOCKHOLDERS' EQUITY - EQUITY PLANS - SCHEDULE OF AGGREGATE STOCK OPTION AND AWARD ACTIVITY (Details) - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Shares Available For Grant |  |  |
Balance at the beginning of the period (in shares) | 18,763,393 |  |
Additional shares authorized (in shares) | 16,755,000 |  |
Stock options granted (in shares) | (19,747,760) |  |
Awards granted (in shares) | (15,962) |  |
Stock options cancelled/forfeited/expired (in shares) | 2,616,058 |  |
Balance at the end of the period (in shares) | 18,370,729 | 18,763,393 |
Number of Shares - Options Outstanding |  |  |
Balance at the beginning of the period (in shares) | 49,952,409 |  |
Stock options granted (in shares) | 19,747,760 |  |
Stock options exercised (in shares) | (1,181,711) |  |
Stock options cancelled/forfeited/expired (in shares) | (2,616,058) |  |
Balance at the end of the period (in shares) | 65,902,400 | 49,952,409 |
Stock options exercisable at the end of the period (in shares) | 36,085,389 | 30,459,136 | 25,721,508
Stock options fully vested and expected to vest at the end of the period (in shares) | 64,539,649 |  |
Weighted Average Exercise Price Per Share - Options Outstanding |  |  |
Balance at the beginning of the period (in dollars per share) | $ 2.06 |  |
Stock options granted (in dollars per share) | 1.37 |  |
Stock options exercised (in dollars per share) | 1.52 |  |
Stock options cancelled/forfeited/expired (in dollars per share) | 1.70 |  |
Balance at the end of the period (in dollars per share) | 1.87 | $ 2.06 |
Stock options exercisable at the end of the period (in dollars per share) | 2.17 | $ 2.35 | $ 2.54
Stock options fully vested and expected to vest at the end of the period (in dollars per share) | $ 1.88 |  |
Weight Average Remaining Contractual Life (in years) - Options Outstanding |  |  |
Balance at the end of the period | 6 years 6 months 21 days |  |
Stock options exercisable at the end of the period | 5 years 1 month 2 days |  |
Stock options fully vested and expected to vest at the end of the period | 6 years 6 months 7 days |  |
Aggregate Intrinsic Value - Options Outstanding |  |  |
Balance at the end of the period (in dollars) | $ 50,205 |  |
Stock options exercisable at the end of the period (in dollars) | 22,878 |  |
Stock options fully vested and expected to vest at the end of the period (in dollars) | $ 48,951 |  |

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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(01) -URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901 + Details
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