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Financial Condition and Business Plan (Details Narrative) - USD ($) |  |  |  | 1 Months Ended | 9 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 16, 2021 | Mar. 19, 2021 | Aug. 28, 2020 | Jun. 18, 2021 | Jan. 31, 2021 | Sep. 30, 2020 | Jun. 30, 2018 | Sep. 30, 2021 | Sep. 29, 2021 | Dec. 31, 2019 | Dec. 31, 2018 | Apr. 05, 2021 | Dec. 31, 2020 | Sep. 30, 2018
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cumulative net losses |  |  |  |  |  |  |  | $ 328,548,285 |  |  |  |  | $ 312,000,341 |
Cash and cash equivalents, restricted cash, short-term investments, interest receivable |  |  |  |  |  |  |  | 60,600,000 |  |  |  |  |  |
Receivable on sale of net operating losses |  |  |  |  |  |  |  | $ 1,850,000 |  |  |  |  |  |
Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from Contributed Capital |  |  |  |  |  |  | $ 10,000,000 |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 10,000,000 |  |  |  |  |  |  |  |  |  |  |
Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.625%
SVB Loan Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Description |  |  |  | Payments under the loan agreement are interest only for the first 24 months after loan closing, followed by a 24-month amortization period of principal and interest through the scheduled maturity date. |  |  |  | Payments under the loan agreement are interest only (calculated based on one-month LIBOR plus 7.625%) for the first 24 months through July 2020, followed by a 21-month amortization period of principal and interest starting on August 1, 2020 and ending through the scheduled maturity date |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 3.25% |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  | $ 10,000,000 |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Remaining Borrowing Capacity |  |  |  | $ 4,000,000 |  |  |  |  |  |  |  |  |  |
SVB Loan Facility [Member] | Silicon Valley Bank [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  |  |  |  |  | $ 10,000,000 |  |  |  |  |  |
Line of Credit Facility, Remaining Borrowing Capacity |  |  |  |  |  |  |  | $ 4,000,000 |  |  |  |  |  |
SVB Loan Facility [Member] | Prime Rate [Member] | Silicon Valley Bank [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  |  |  |  |  | 3.25% |  |  |  |  |  |
SVB Loan Facility [Member] | Horizon Technology Finance Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repayment of outstanding in-debtedness amount |  |  |  |  |  |  |  | $ 6,000,000 |  |  |  |  |  |
Amendment to Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repayments of Notes Payable |  |  | 5,000,000 |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | 5,000,000 |  |  |  |  |  |  |  |  |  |  |
Debt instrument related end term charges |  |  | $ 200,000 |  |  |  |  |  |  |  |  |  |  |
Capital on DemandTM Sales Agreement [Member] | Jones Trading Institutional Services, LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents, restricted cash, short-term investments, interest receivable |  |  |  |  |  |  |  | 60,600,000 |  |  |  |  |  |
Proceeds from Contributed Capital |  | $ 6,900,000 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  | $ 35,000,000 |  |  |  |  |  |  | $ 15,000,000 |  |
Proceeds from Warrant Exercises |  |  |  |  | $ 1,500,000 |  |  |  |  |  |  |  |  |
New Jersey [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds from sale of net operating losses | $ 1,600,000 |  |  |  |  | $ 2,000,000.0 |  | $ 20,000,000 | $ 15,000,000 | $ 12,200,000 | $ 13,000,000 |  |  |
New Jersey [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds from sale of net operating losses | $ 1,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |

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