Accrued Expenses (Details) - USD ($)	Mar. 31, 2018		Dec. 31, 2017
Accrued Expenses [Abstract]
Accrued research and development costs	$ 7,729,749	[1]	$ 2,857,025
Accrued professional fees	245,773		267,646
Accrued compensation	102,715		1,886,638
Accrued other	367,336		385,896
Deferred rent	27,308		25,000
Total	8,472,881		$ 5,422,205
Accrued close down NEWTON 2 trial costs	2,900,000
Accrued CMO milestone payments	$ 2,000,000

[1] Balance as of March 31, 2018 includes estimated close down NEWTON 2 trial costs of $2.9 million and $2.0 million for CMO milestone payments.