NET LOSS PER SHARE - Anti-dilutive Securities (Details) - shares
shares in Thousands |
12 Months Ended |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
92,821
|
381,643
|
333,038
|
| Warrants |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
19,933
|
3,370
|
3,366
|
| Series D Preferred Stock Warrants |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
|
485
|
9,090
|
| Series E Preferred Stock Warrants |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
|
121
|
|
| RSU |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
46,525
|
22,758
|
912
|
| Stock option |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
24,158
|
36,609
|
44,066
|
| Unvested Shares from Early Exercise |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
57
|
187
|
1,120
|
| Vesting of restricted shares |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
2,148
|
3,689
|
2,994
|
| Redeemable convertible preferred stock outstanding |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Total anti-dilutive securities |
|
314,424
|
271,490
|