Fair Value of Warrants - Assumptions Used in Computing Fair Value of Derivative Warrants (Details) - $ / shares |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2020 |
Dec. 31, 2019 |
|
| Class of Warrant or Right [Line Items] | ||
| Exercise price (usd per share) | $ 104.18 | |
| 2016 Offering | ||
| Class of Warrant or Right [Line Items] | ||
| Exercise price (usd per share) | $ 67.50 | $ 67.50 |
| Expected life (years) | 1 year 6 months 29 days | 2 years 29 days |
| Expected volatility | 2016 Offering | ||
| Class of Warrant or Right [Line Items] | ||
| Measurement input assumption (as a percent) | 157.09% | 150.69% |
| Risk-free interest rate | 2016 Offering | ||
| Class of Warrant or Right [Line Items] | ||
| Measurement input assumption (as a percent) | 0.16% | 1.58% |
| Expected dividend yield | 2016 Offering | ||
| Class of Warrant or Right [Line Items] | ||
| Measurement input assumption (as a percent) | 0.00% | 0.00% |
| X | ||||||||||
- Definition Warrants and Rights Outstanding, Measurement Input, Percent No definition available.
|
| X | ||||||||||
- Definition Exercise price per share or per unit of warrants or rights outstanding. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition 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. No definition available.
|
| X | ||||||||||
- Definition Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|