STOCKHOLDERS’ EQUITY - Common Stock Reserved for Issuance (Details) - shares	Mar. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Common shares reserved for future issuance (in shares)	190,805,032	210,204,258
Private warrants to purchase common stock
Class of Stock [Line Items]
Common shares reserved for future issuance (in shares)	44,350,000	44,350,000
Stock options outstanding
Class of Stock [Line Items]
Common shares reserved for future issuance (in shares)	50,700,238	64,119,902
Restricted stock units outstanding
Class of Stock [Line Items]
Common shares reserved for future issuance (in shares)	34,235,618	48,234,611
Shares available for future grants under equity plans
Class of Stock [Line Items]
Common shares reserved for future issuance (in shares)	24,781,391	16,761,960
If-converted common shares from convertible note
Class of Stock [Line Items]
Common shares reserved for future issuance (in shares)	36,737,785	36,737,785