Consolidated Statements of Changes in Redeemable Common Stock and Stockholders' Equity (Deficit) - USD ($)	Redeemable Common Stock IPO	Redeemable Common Stock	Class D Preferred Stock IPO	Class D Preferred Stock	Class C Preferred Stock IPO	Class C Preferred Stock Deerfield Convertible Note	Class C Preferred Stock	Class B-1 Preferred Stock IPO	Class B-1 Preferred Stock Class B Note	Class B-1 Preferred Stock	Common Stock IPO	Common Stock Follow-On Offering	Common Stock	Additional Paid-in Capital IPO	Additional Paid-in Capital Follow-On Offering	Additional Paid-in Capital Class B Note	Additional Paid-in Capital Deerfield Convertible Note	Additional Paid-in Capital	Accumulated Deficit	IPO	Follow-On Offering	Class B Note	Deerfield Convertible Note	Total
Balance at the beginning of the period at Dec. 31, 2013		$ 345,447
Balance at the beginning of the period (in shares) at Dec. 31, 2013		331,053
Increase (Decrease) in Redeemable Common Stock
Issuance of redeemable common stock at fair value		$ 214,298
Issuance of redeemable common stock at fair value (in shares)		86,725
Shares conversion amount													$ (122)
Shares conversion (in shares)													(1,214,077)
Balance at the end of the period at Dec. 31, 2014		$ 559,745
Balance at the end of the period (in shares) at Dec. 31, 2014		417,778
Balance at the beginning of the period at Dec. 31, 2013													$ 706					$ 2,727,038	$ (4,370,843)					$ (1,643,099)
Balance at the beginning of the period (in shares) at Dec. 31, 2013													7,061,173
Increase (Decrease) in Stockholders' Equity (Deficit)
Stock-based compensation - restricted stock																		5,749,774
Stock based compensation-restricted stock													$ 59											5,749,833
Stock based compensation-restricted stock (in shares)													583,597
Stock-based compensation - stock options																		416,624						416,624
Stock-based compensation - stock warrants																		243,863						243,863
Stock-based compensation - shares exchange																		193,549						193,549
Stock-based compensation - share grants																		594,088						594,088
Shares conversion amount													$ (122)
Share exchanges										$ 122
Share exchanges (in shares)										1,214,077
Issuance of Class B-1 preferred stock and B-2 warrants										$ 81								1,999,919						2,000,000
Conversion of convertible debt						$ 13			$ 20													$ 612,835	$ 503,424	1,000,000
Conversion of convertible debt (in shares)						126,991			202,345
Conversion of convertible debt																$ 612,815	$ 503,411
Issuance of Class C Milestone Shares							$ 113											4,499,921						4,500,034
Issuance of stock (in shares)							1,135,084			809,385
Issuance of common stock to vendor													$ 4					102,296						102,300
Issuance of common stock to vendor (in shares)													41,400
Net loss																			(15,705,776)					(15,705,776)
Balance at the end of the period at Dec. 31, 2014							$ 126			$ 223			$ 647					17,643,298	(20,076,619)					(2,432,325)
Balance at the end of the period (in shares) at Dec. 31, 2014							1,262,075			2,225,807			6,472,093
Increase (Decrease) in Redeemable Common Stock
Issuance of redeemable common stock at fair value		$ 473,164
Issuance of redeemable common stock at fair value (in shares)		38,265
Balance at the end of the period at Dec. 31, 2015		$ 1,032,909																						$ 1,032,909
Balance at the end of the period (in shares) at Dec. 31, 2015		456,043																						456,043
Increase (Decrease) in Stockholders' Equity (Deficit)
Stock-based compensation - restricted stock																		19,322,275						$ 19,322,275
Stock-based compensation - stock options																		5,250,217						5,250,217
Stock-based compensation - stock warrants																		358,637						358,637
Issuance of Class D preferred stock				$ 309														64,787,240						64,787,549
Issuance of Class C Milestone Shares							$ 111											4,999,909						5,000,020
Issuance of Class B-1 Milestone Shares										$ 101								2,499,899						2,500,000
Exercise of stock options													$ 21					520,585						520,606
Exercise of stock options (in shares)													207,000
Exercise of stock warrant													$ 14					340,986						341,000
Exercise of stock warrant (in shares)													138,000
Issuance of stock (in shares)				3,093,092			1,102,945			1,011,721
Sixeva Liquidation																			(57)					(57)
Net loss																			(38,473,844)					(38,473,844)
Balance at the end of the period at Dec. 31, 2015				$ 309			$ 237			$ 324			$ 682					115,723,046	(58,550,520)					$ 57,174,078
Balance at the end of the period (in shares) at Dec. 31, 2015				3,093,092			2,365,020			3,237,528			6,817,093
Increase (Decrease) in Redeemable Common Stock
Shares conversion amount	$ (1,032,909)		$ (309)		$ (237)			$ (324)
Shares conversion (in shares)	(456,043)		(3,093,092)		(2,365,020)			(3,237,528)
Balance at the end of the period (in shares) at Dec. 31, 2016																								0
Increase (Decrease) in Stockholders' Equity (Deficit)
Stock based compensation-restricted stock													$ 175					10,370,762						$ 10,370,937
Stock based compensation-restricted stock (in shares)													1,750,794
Stock-based compensation - stock options																		16,415,008						16,415,008
Shares conversion amount	$ (1,032,909)		$ (309)		$ (237)			$ (324)
Share conversion, converted to common stock											$ 870			$ (892)						$ (892)
Share conversion, converted to common stock (in shares)											8,695,640
Exercise of stock options													$ 8					429,707						429,715
Exercise of stock options (in shares)													84,127
Exercise of stock warrant													$ 2					53,348						53,350
Exercise of stock warrant (in shares)													20,771
Shares converted to redeemable common stock amount											$ 45			1,032,864						1,032,909
Shares converted to redeemable common stock (in shares)											456,043
Issuance of stock											$ 528	$ 460		$ 95,348,158	$ 148,319,207					$ 95,348,686	$ 148,319,667
Issuance of stock (in shares)											5,277,941	4,597,645
Net loss																			(83,011,804)					(83,011,804)
Balance at the end of the period at Dec. 31, 2016													$ 2,770					$ 387,691,208	$ (141,562,324)					$ 246,131,654
Balance at the end of the period (in shares) at Dec. 31, 2016													27,700,054