Nature of Operations and Summary of Significant Accounting Policies (Tables)
   | 
12 Months Ended | 
Dec. 31, 2019  | 
| Schedule of Statement of Operations | 
 The table below presents the impact
of the adoption of ASC 606 on our statement of operations for the year ended December 31, 2018. 
  
    |   | 
      | 
    For the year ended December 31, 2018 | 
      | 
 
    |   | 
      | 
    Under | 
      | 
      | 
    Effect of | 
      | 
      | 
    As Reported | 
      | 
 
    |   | 
      | 
    ASC 605 | 
      | 
      | 
    ASC 606 | 
      | 
      | 
    Under ASC 606 | 
      | 
 
    | Revenues | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Foundation revenues | 
      | 
    $ | 
    - | 
      | 
      | 
    $ | 
    2,796,000 | 
      | 
      | 
    $ | 
    2,796,000 | 
      | 
 
    | License revenues | 
      | 
      | 
    602,000 | 
      | 
      | 
      | 
    (602,000 | 
    ) | 
      | 
      | 
    - | 
      | 
 
    | Total revenues | 
      | 
      | 
    804,000 | 
      | 
      | 
      | 
    2,194,000 | 
      | 
      | 
      | 
    2,998,000 | 
      | 
 
    | Loss from operations | 
      | 
      | 
    (60,360,000 | 
    ) | 
      | 
      | 
    2,194,000 | 
      | 
      | 
      | 
    (58,166,000 | 
    ) | 
 
    | Net loss | 
      | 
      | 
    (58,865,000 | 
    ) | 
      | 
      | 
    2,194,000 | 
      | 
      | 
      | 
    (56,671,000 | 
    ) | 
 
    | Basic and diluted loss per common share | 
      | 
      | 
    (1.24 | 
    ) | 
      | 
      | 
    0.05 | 
      | 
      | 
      | 
    (1.19 | 
    ) | 
 
 
 | 
| Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share | 
 We did not include the following
potentially dilutive securities in the computation of diluted net loss per common share during the periods presented: 
  
    |   | 
      | 
    For the years ended December 31, | 
      | 
 
    |   | 
      | 
    2019 | 
      | 
      | 
    2018 | 
      | 
      | 
    2017 | 
      | 
 
    | Warrants | 
      | 
      | 
    70,000 | 
      | 
      | 
      | 
    1,820,686 | 
      | 
      | 
      | 
    2,934,685 | 
      | 
 
    | Stock options | 
      | 
      | 
    6,055,395 | 
      | 
      | 
      | 
    5,841,805 | 
      | 
      | 
      | 
    5,429,727 | 
      | 
 
    | Total | 
      | 
      | 
    6,125,395 | 
      | 
      | 
      | 
    7,662,491 | 
      | 
      | 
      | 
    8,364,412 | 
      | 
 
 
 | 
| Schedule of Stock Based Compensation | 
 The following table summarizes stock
option-based option compensation for 2019, 2018 and 2017, which was allocated as follows: 
  
    |   | 
      | 
    For the years ended December 31, | 
      | 
 
    |   | 
      | 
    2019 | 
      | 
      | 
    2018 | 
      | 
      | 
    2017 | 
      | 
 
    | Research and development | 
      | 
    $ | 
    3,932,000 | 
      | 
      | 
    $ | 
    3,913,000 | 
      | 
      | 
    $ | 
    1,668,000 | 
      | 
 
    | General and administrative | 
      | 
      | 
    3,406,000 | 
      | 
      | 
      | 
    4,265,000 | 
      | 
      | 
      | 
    2,976,000 | 
      | 
 
    | Stock option-based compensation expense included in operating expense | 
      | 
      | 
    7,338,000 | 
      | 
      | 
      | 
    8,178,000 | 
      | 
      | 
      | 
    4,644,000 | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Total stock option-based compensation expense | 
      | 
      | 
    7,338,000 | 
      | 
      | 
      | 
    8,178,000 | 
      | 
      | 
      | 
    4,644,000 | 
      | 
 
    | Tax benefit | 
      | 
      | 
    - | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    - | 
      | 
 
    | Stock option-based compensation expense, net of tax | 
      | 
    $ | 
    7,338,000 | 
      | 
      | 
    $ | 
    8,178,000 | 
      | 
      | 
    $ | 
    4,644,000 | 
      | 
 
 
 | 
| Restricted Stock [Member] | 
 
 | 
| Schedule of Stock Based Compensation | 
 The following table summarizes restricted
stock-based compensation for 2019, 2018 and 2017, which was allocated as follows: 
  
    |   | 
      | 
    For the years ended December 31, | 
      | 
 
    |   | 
      | 
    2019 | 
      | 
      | 
    2018 | 
      | 
      | 
    2017 | 
      | 
 
    | Research and development | 
      | 
    $ | 
    454,000 | 
      | 
      | 
    $ | 
    - | 
      | 
      | 
    $ | 
    - | 
      | 
 
    | General and administrative | 
      | 
      | 
    445,000 | 
      | 
      | 
      | 
    688,000 | 
      | 
      | 
      | 
    1,272,000 | 
      | 
 
    | Restricted stock-based compensation expense included in operating expense | 
      | 
      | 
    899,000 | 
      | 
      | 
      | 
    688,000 | 
      | 
      | 
      | 
    1,272,000 | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Total restricted stock-based compensation expense | 
      | 
      | 
    899,000 | 
      | 
      | 
      | 
    688,000 | 
      | 
      | 
      | 
    1,272,000 | 
      | 
 
    | Tax benefit | 
      | 
      | 
    - | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    - | 
      | 
 
    | Restricted stock-based compensation expense, net of tax | 
      | 
    $ | 
    899,000 | 
      | 
      | 
    $ | 
    688,000 | 
      | 
      | 
    $ | 
    1,272,000 | 
      | 
 
 
 |