STOCK-BASED COMPENSATION - Stock Options (Details) - Options to purchase common stock and unvested RSUs - $ / shares | 12 Months Ended |
Dec. 31, 2021 | Dec. 31, 2020 |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Outstanding Options, Number Outstanding | 44,940,169 | 47,454,759 |
Outstanding Options, Weighted Average Remaining Contractual life | 6 years 3 months 21 days | 6 years 8 months 12 days |
Options Exercisable, Number Outstanding | 30,931,099 | 28,897,348 |
Options Exercisable, Weighted Average Remaining Contractual life | 5 years 4 months 20 days | 5 years 5 months 12 days |
$0.010 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 0.010 | $ 0.01 |
Outstanding Options, Number Outstanding | 6,890,341 | 2,825,937 |
Outstanding Options, Weighted Average Remaining Contractual life | 8 years 8 months 12 days | 9 years 2 months 15 days |
Options Exercisable, Number Outstanding | 643,753 | |
Options Exercisable, Weighted Average Remaining Contractual life | 8 years 1 month 20 days | 0 years |
$0.080 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 0.080 | |
Outstanding Options, Number Outstanding | 318,239 | |
Outstanding Options, Weighted Average Remaining Contractual life | 5 years 5 months 4 days | |
Options Exercisable, Number Outstanding | 300,549 | |
Options Exercisable, Weighted Average Remaining Contractual life | 5 years 4 months 20 days | |
$0.02 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 0.02 |
Outstanding Options, Number Outstanding | | 513,826 |
Outstanding Options, Weighted Average Remaining Contractual life | | 3 months 25 days |
Options Exercisable, Number Outstanding | | 513,826 |
Options Exercisable, Weighted Average Remaining Contractual life | | 3 months 25 days |
$0.140 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 0.140 | |
Outstanding Options, Number Outstanding | 99,959 | |
Outstanding Options, Weighted Average Remaining Contractual life | 8 months 23 days | |
Options Exercisable, Number Outstanding | 99,959 | |
Options Exercisable, Weighted Average Remaining Contractual life | 8 months 23 days | |
$0.08 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 0.08 |
Outstanding Options, Number Outstanding | | 460,701 |
Outstanding Options, Weighted Average Remaining Contractual life | | 4 years 9 months 10 days |
Options Exercisable, Number Outstanding | | 372,251 |
Options Exercisable, Weighted Average Remaining Contractual life | | 4 years 2 months 19 days |
$0.350 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 0.350 | |
Outstanding Options, Number Outstanding | 71,507 | |
Outstanding Options, Weighted Average Remaining Contractual life | 1 year 10 months 9 days | |
Options Exercisable, Number Outstanding | 71,507 | |
Options Exercisable, Weighted Average Remaining Contractual life | 1 year 10 months 9 days | |
$0.14 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 0.14 |
Outstanding Options, Number Outstanding | | 389,035 |
Outstanding Options, Weighted Average Remaining Contractual life | | 1 year 11 months 19 days |
Options Exercisable, Number Outstanding | | 389,035 |
Options Exercisable, Weighted Average Remaining Contractual life | | 1 year 11 months 19 days |
$0.540 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 0.540 | |
Outstanding Options, Number Outstanding | 1,641,129 | |
Outstanding Options, Weighted Average Remaining Contractual life | 2 years 5 months 12 days | |
Options Exercisable, Number Outstanding | 1,641,129 | |
Options Exercisable, Weighted Average Remaining Contractual life | 2 years 5 months 12 days | |
$0.35 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 0.35 |
Outstanding Options, Number Outstanding | | 148,050 |
Outstanding Options, Weighted Average Remaining Contractual life | | 2 years 10 months 9 days |
Options Exercisable, Number Outstanding | | 148,050 |
Options Exercisable, Weighted Average Remaining Contractual life | | 2 years 10 months 9 days |
$0.620 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 0.620 | |
Outstanding Options, Number Outstanding | 3,283,033 | |
Outstanding Options, Weighted Average Remaining Contractual life | 3 years 3 days | |
Options Exercisable, Number Outstanding | 3,283,033 | |
Options Exercisable, Weighted Average Remaining Contractual life | 3 years 3 days | |
$0.54 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 0.54 |
Outstanding Options, Number Outstanding | | 2,843,996 |
Outstanding Options, Weighted Average Remaining Contractual life | | 3 years 4 months 2 days |
Options Exercisable, Number Outstanding | | 2,843,996 |
Options Exercisable, Weighted Average Remaining Contractual life | | 3 years 4 months 2 days |
$1.380 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 1.380 | |
Outstanding Options, Number Outstanding | 620,637 | |
Outstanding Options, Weighted Average Remaining Contractual life | 3 years 9 months 14 days | |
Options Exercisable, Number Outstanding | 620,637 | |
Options Exercisable, Weighted Average Remaining Contractual life | 3 years 9 months 14 days | |
$0.62 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 0.62 |
Outstanding Options, Number Outstanding | | 3,799,325 |
Outstanding Options, Weighted Average Remaining Contractual life | | 4 years 18 days |
Options Exercisable, Number Outstanding | | 3,799,325 |
Options Exercisable, Weighted Average Remaining Contractual life | | 4 years 18 days |
$1.410 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 1.410 | |
Outstanding Options, Number Outstanding | 5,362,160 | |
Outstanding Options, Weighted Average Remaining Contractual life | 4 years 21 days | |
Options Exercisable, Number Outstanding | 5,362,160 | |
Options Exercisable, Weighted Average Remaining Contractual life | 4 years 21 days | |
$1.38 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 1.38 |
Outstanding Options, Number Outstanding | | 979,480 |
Outstanding Options, Weighted Average Remaining Contractual life | | 4 years 11 months 12 days |
Options Exercisable, Number Outstanding | | 979,480 |
Options Exercisable, Weighted Average Remaining Contractual life | | 4 years 11 months 12 days |
$1.810 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 1.810 | |
Outstanding Options, Number Outstanding | 495,275 | |
Outstanding Options, Weighted Average Remaining Contractual life | 3 years 11 months 4 days | |
Options Exercisable, Number Outstanding | 495,275 | |
Options Exercisable, Weighted Average Remaining Contractual life | 3 years 11 months 4 days | |
$1.41 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 1.41 |
Outstanding Options, Number Outstanding | | 5,880,952 |
Outstanding Options, Weighted Average Remaining Contractual life | | 4 years 11 months 12 days |
Options Exercisable, Number Outstanding | | 5,880,952 |
Options Exercisable, Weighted Average Remaining Contractual life | | 4 years 11 months 12 days |
$2.740 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 2.740 | |
Outstanding Options, Number Outstanding | 5,534,285 | |
Outstanding Options, Weighted Average Remaining Contractual life | 8 years 1 month 17 days | |
Options Exercisable, Number Outstanding | 2,531,209 | |
Options Exercisable, Weighted Average Remaining Contractual life | 8 years 3 days | |
$1.81 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 1.81 |
Outstanding Options, Number Outstanding | | 706,880 |
Outstanding Options, Weighted Average Remaining Contractual life | | 5 years 5 months 15 days |
Options Exercisable, Number Outstanding | | 706,880 |
Options Exercisable, Weighted Average Remaining Contractual life | | 5 years 5 months 15 days |
$2.800 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 2.800 | |
Outstanding Options, Number Outstanding | 5,334,695 | |
Outstanding Options, Weighted Average Remaining Contractual life | 5 years 11 months 8 days | |
Options Exercisable, Number Outstanding | 5,123,696 | |
Options Exercisable, Weighted Average Remaining Contractual life | 5 years 11 months 8 days | |
$2.74 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 2.74 |
Outstanding Options, Number Outstanding | | 6,291,514 |
Outstanding Options, Weighted Average Remaining Contractual life | | 9 years 2 months 23 days |
Options Exercisable, Number Outstanding | | 3,883,167 |
Options Exercisable, Weighted Average Remaining Contractual life | | 5 years 9 months 10 days |
$2.850. | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 2.850 | |
Outstanding Options, Number Outstanding | 1,360,598 | |
Outstanding Options, Weighted Average Remaining Contractual life | 6 years 8 months 23 days | |
Options Exercisable, Number Outstanding | 1,235,549 | |
Options Exercisable, Weighted Average Remaining Contractual life | 6 years 8 months 15 days | |
$2.80 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 2.80 |
Outstanding Options, Number Outstanding | | 6,052,744 |
Outstanding Options, Weighted Average Remaining Contractual life | | 6 years 10 months 6 days |
Options Exercisable, Number Outstanding | | 4,247,210 |
Options Exercisable, Weighted Average Remaining Contractual life | | 6 years 8 months 26 days |
$2.850 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 2.850 | |
Outstanding Options, Number Outstanding | 47,000 | |
Outstanding Options, Weighted Average Remaining Contractual life | 9 years 8 months 8 days | |
Options Exercisable, Number Outstanding | 11,750 | |
Options Exercisable, Weighted Average Remaining Contractual life | 9 years 8 months 8 days | |
$2.85 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 2.85 |
Outstanding Options, Number Outstanding | | 1,743,275 |
Outstanding Options, Weighted Average Remaining Contractual life | | 7 years 8 months 1 day |
Options Exercisable, Number Outstanding | | 971,053 |
Options Exercisable, Weighted Average Remaining Contractual life | | 7 years 7 months 9 days |
$2.900 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 2.900 | |
Outstanding Options, Number Outstanding | 7,359,646 | |
Outstanding Options, Weighted Average Remaining Contractual life | 7 years 7 days | |
Options Exercisable, Number Outstanding | 5,171,048 | |
Options Exercisable, Weighted Average Remaining Contractual life | 6 years 11 months 19 days | |
$2.90 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 2.90 |
Outstanding Options, Number Outstanding | | 8,120,490 |
Outstanding Options, Weighted Average Remaining Contractual life | | 8 years 10 days |
Options Exercisable, Number Outstanding | | 3,602,295 |
Options Exercisable, Weighted Average Remaining Contractual life | | 7 years 11 months 1 day |
$3.020 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 3.020 | |
Outstanding Options, Number Outstanding | 3,436,058 | |
Outstanding Options, Weighted Average Remaining Contractual life | 5 years 29 days | |
Options Exercisable, Number Outstanding | 3,436,058 | |
Options Exercisable, Weighted Average Remaining Contractual life | 5 years 29 days | |
$3.02 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 3.02 |
Outstanding Options, Number Outstanding | | 4,189,177 |
Outstanding Options, Weighted Average Remaining Contractual life | | 5 years 9 months 25 days |
Options Exercisable, Number Outstanding | | 365,953 |
Options Exercisable, Weighted Average Remaining Contractual life | | 8 years 5 months 19 days |
$3.070 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 3.070 | |
Outstanding Options, Number Outstanding | 879,566 | |
Outstanding Options, Weighted Average Remaining Contractual life | 7 years 5 months 15 days | |
Options Exercisable, Number Outstanding | 551,738 | |
Options Exercisable, Weighted Average Remaining Contractual life | 7 years 4 months 24 days | |
$3.07 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 3.07 |
Outstanding Options, Number Outstanding | | 1,095,617 |
Outstanding Options, Weighted Average Remaining Contractual life | | 8 years 6 months 10 days |
Options Exercisable, Number Outstanding | | 193,875 |
Options Exercisable, Weighted Average Remaining Contractual life | | 9 years 2 months 15 days |
$3.900 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 3.900 | |
Outstanding Options, Number Outstanding | 1,184,889 | |
Outstanding Options, Weighted Average Remaining Contractual life | 8 years 10 months 2 days | |
Options Exercisable, Number Outstanding | 352,049 | |
Options Exercisable, Weighted Average Remaining Contractual life | 8 years 6 months 21 days | |
$3.90 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | | $ 3.90 |
Outstanding Options, Number Outstanding | | 1,413,760 |
Outstanding Options, Weighted Average Remaining Contractual life | | 9 years 11 months 12 days |
Options Exercisable, Weighted Average Remaining Contractual life | | 0 years |
$7.870 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 7.870 | |
Outstanding Options, Number Outstanding | 983,552 | |
Outstanding Options, Weighted Average Remaining Contractual life | 9 years 1 month 6 days | |
Options Exercisable, Weighted Average Remaining Contractual life | 0 years | |
$9.990 | | |
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] | | |
Exercise Price | $ 9.990 | |
Outstanding Options, Number Outstanding | 37,600 | |
Outstanding Options, Weighted Average Remaining Contractual life | 9 years 8 months 8 days | |
Options Exercisable, Weighted Average Remaining Contractual life | 0 years | |