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Equity - Narrative (Details) |  |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Aug. 06, 2020 USD ($) | Jul. 28, 2020 USD ($) | Jun. 11, 2020 USD ($) $ / shares shares | Dec. 18, 2019 USD ($) $ / shares shares | Aug. 31, 2017 USD ($) | Mar. 31, 2021 USD ($) vote $ / shares shares | Mar. 31, 2020 USD ($) | Dec. 31, 2020 USD ($) $ / shares shares | Aug. 31, 2020 $ / shares
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Shares issued, value |  |  |  |  |  | $ 20,991,000 | $ 1,141,000 |  |
Class of warrant or right, outstanding (in shares) | shares |  |  |  |  |  | 12,378,016,000 |  |  |
Exercise price (in dollars per share) | $ / shares |  |  |  |  |  | $ 1.60 |  |  | $ 2.54
Warrant liabilities |  |  |  |  |  | $ 45,455,000 |  | $ 28,708,000 |
Common stock, shares authorized (in shares) | shares |  |  |  |  |  | 200,000,000 |  | 200,000,000 |
Common stock, par value (in dollars per share) | $ / shares |  |  |  |  |  | $ 0.0001 |  | $ 0.0001 |
Common stock, shares issued | shares |  |  |  |  |  | 112,977,004 |  | 108,071,249 |
Common stock, shares outstanding | shares |  |  |  |  |  | 112,977,004 |  | 108,071,249 |
Number of votes per share that common stockholders are entitled to | vote |  |  |  |  |  | 1 |  |  |
Dividends declared or paid on common stock |  |  |  |  |  | $ 0 |  |  |
Exercise of common warrants |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Class of warrant or right, outstanding (in shares) | shares |  |  |  |  |  | 292,469,000 |  |  |
August 2020 Shelf Registration Statement |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Sale common stock | $ 200,000,000.0 |  |  |  |  |  |  |  |
At-The-Market Offering |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Sale common stock |  |  |  |  | $ 50,000,000.0 |  |  |  |
Sale of stock, number of shares issued in transaction (in shares) | shares |  |  |  |  |  | 4,706,844 |  | 1,069,486 |
Share price (in dollars per share) | $ / shares |  |  |  |  |  | $ 4.59 |  | $ 2.16 |
Shares issued, value |  |  |  |  |  | $ 20,900,000 |  | $ 2,100,000 |
2020 Sale Agreement - At-the-Market Offering |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Sale common stock |  |  |  |  | $ 50,000,000.0 |  |  |  |
SOBI Purchase Agreement |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Sale common stock |  |  | $ 25,000,000.0 |  |  |  |  |  |
Sale of stock, number of shares issued in transaction (in shares) | shares |  |  | 5,416,390 |  |  |  |  |  |
Share price (in dollars per share) | $ / shares |  |  | $ 4.6156 |  |  |  |  |  |
Sale of stock, percentage of ten-day volume weighted average price of common stock |  |  | 120.00% |  |  |  |  |  |
Lock-up from closing, term |  |  |  |  |  | 1 year |  |  |
Redemption premium |  | $ 14,500,000 |  |  |  |  |  |  |
December 2019 Financing |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Sale common stock |  |  |  | $ 65,600,000 |  |  |  |  |
Sale of stock, number of shares issued in transaction (in shares) | shares |  |  |  | 37,634,883 |  |  |  |  |
Share price (in dollars per share) | $ / shares |  |  |  | $ 1.46 |  |  |  |  |
Class of warrant or right, outstanding (in shares) | shares |  |  |  | 22,988,501 |  |  |  |  |
Warrant Issued |  |  |  | $ 40,700,000 |  |  |  |  |
Issuance costs |  |  |  |  |  |  | 4,400,000 |  |
Warrant liabilities |  |  |  |  |  | $ 45,500,000 |  |  |
Warrant, increase (decrease) in equity, amount |  |  |  |  |  | $ (16,700,000) | $ (800,000) |  |
December 2019 Financing | Pre-Funded Warrant |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Class of warrant or right, number of warrants exercised (in shares) | shares |  |  |  | 8,342,128 |  |  |  |  |
Exercise price (in dollars per share) | $ / shares |  |  |  | $ 0.0001 |  |  |  |  |
December 2019 Financing | Common Warrant |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Share price (in dollars per share) | $ / shares |  |  |  | 0.125 |  |  |  |  |
Exercise price (in dollars per share) | $ / shares |  |  |  | $ 1.46 |  |  |  |  |
2017 PIPE |  |  |  |  |  |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |  |  |  |  |  |
Common stock, shares authorized (in shares) | shares |  |  |  |  |  | 200,000,000 |  |  |
Common stock, par value (in dollars per share) | $ / shares |  |  |  |  |  | $ 0.0001 |  |  |

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