| Nature of Operations and Summary of Significant Accounting Policies - Schedule of Statement of Operations (Details) - USD ($) | 3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | |
| Total revenues | $ 2,998,000 | $ 837,000 | |||||||||
| Loss from operations | $ (16,411,000) | $ (17,649,000) | $ (23,976,000) | $ (19,054,000) | $ (18,010,000) | $ (16,916,000) | $ (12,557,000) | $ (10,683,000) | (77,090,000) | (58,166,000) | (27,836,000) | 
| Net loss | $ (16,431,000) | $ (17,372,000) | $ (23,924,000) | $ (18,555,000) | $ (17,479,000) | $ (16,419,000) | $ (12,243,000) | $ (10,530,000) | $ (76,282,000) | $ (56,671,000) | $ (27,319,000) | 
| Basic and diluted loss per common share | $ (0.30) | $ (0.35) | $ (0.49) | $ (0.39) | $ (0.36) | $ (0.34) | $ (0.26) | $ (0.22) | $ (1.51) | $ (1.19) | $ (0.66) | 
| Foundation Revenues [Member] | |||||||||||
| Total revenues | $ 369,000 | $ 1,687,000 | $ 259,000 | $ 481,000 | $ 2,796,000 | ||||||
| License Revenues[Member] | |||||||||||
| Total revenues | $ 602,000 | ||||||||||
| Under ASC 605 [Member] | |||||||||||
| Total revenues | 804,000 | ||||||||||
| Loss from operations | (60,360,000) | ||||||||||
| Net loss | $ (58,865,000) | ||||||||||
| Basic and diluted loss per common share | $ (1.24) | ||||||||||
| Under ASC 605 [Member] | Foundation Revenues [Member] | |||||||||||
| Total revenues | |||||||||||
| Under ASC 605 [Member] | License Revenues[Member] | |||||||||||
| Total revenues | 602,000 | ||||||||||
| Effect of ASC 606 [Member] | |||||||||||
| Total revenues | 2,194,000 | ||||||||||
| Loss from operations | 2,194,000 | ||||||||||
| Net loss | $ 2,194,000 | ||||||||||
| Basic and diluted loss per common share | $ 0.05 | ||||||||||
| Effect of ASC 606 [Member] | Foundation Revenues [Member] | |||||||||||
| Total revenues | $ 2,796,000 | ||||||||||
| Effect of ASC 606 [Member] | License Revenues[Member] | |||||||||||
| Total revenues | $ (602,000) | ||||||||||