CONVERTIBLE NOTES - 2019 Convertible Notes (Details) - Convertible promissory notes - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Jan. 31, 2020
Exchange Transaction
Fair value of convertible debt		$ 15.4
2019 Convertible Notes
Debt Instrument [Line Items]
Proceeds from loan	$ 65.5
Proceeds from related parties	$ 54.5
Fixed interest rate, annual	8.00%
Maturity date, extension period	6 months
Debt issuance costs	$ 2.3
Expected life of notes	1 year
Warrant liabilities	$ 4.0
Exchange Transaction
Fair value of convertible debt	36.5
Fair value of warrants	4.0
Fair value of preferred stock	71.4
Cash paid in exchange transaction	35.6
Carrying value of preferred and common equity exchange	87.3
Effect of exchange transaction	$ 11.0
2019 Convertible Notes \| 2019 Preferred Stock Warrants
Debt Instrument [Line Items]
Warrants issued	23,177,068

The carrying value of common and preferred stock exchanged in a transaction.

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Cash paid in an exchange transaction.

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The period of time which the maturity date can be extended at the election of a majority of the note holders.

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Portion of proceeds from issuance of debt that is from related parties.

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The decrease in temporary and stockholders' equity due to an exchange of temporary and other equity instruments.

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The number of warrants issued during the period.

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Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

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Contractual interest rate for funds borrowed, under the debt agreement.

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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.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Fair value portion of shares that an entity is required to redeem for cash or other assets at a fixed or determinable date or upon the occurrence of an event.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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The amount that is required to be paid, determined under the conditions specified in the contract, if as of the reporting date, the holder of the share has exercised the right to or the shares are mandatorily redeemable after one year from the reporting date or operating cycle, if longer.

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The fair value of shares that would be issued, determined under the conditions specified in the contract if the settlement were to occur at the reporting date.

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