CONSOLIDATED STATEMENT OF OPERATIONS - USD ($)	10 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net product revenue	$ 0	$ 989,918	$ 0
Other revenue	0	20,745	0
Total revenue	0	1,010,663	0
Costs and expenses:
Cost of product revenue	0	662,747	0
Research and development	4,003,911	20,378,161	12,749,379
Selling, general and administrative	4,025,895	19,855,987	16,464,279
Total costs and expenses	8,029,806	40,896,895	29,213,658
Loss from operations	(8,029,806)	(39,886,232)	(29,213,658)
Interest income, net	18,946	393,109	72,028
Net loss	(8,010,860)	(39,493,123)	(29,141,630)
Net loss attributable to common stockholders	$ (8,010,860)	$ (39,493,123)	$ (29,141,630)
Net loss per share attributable to common stockholders - basic and diluted (in usd per share)	$ (4.57)	$ (2.43)	$ (2.08)
Weighted-average number of common shares outstanding — basic and diluted	1,753,024	16,233,985	14,032,916