Condensed Consolidated Statements of Redeemable Convertible Preferred Units/Shares and Changes in Members'/Stockholders' Equity (unaudited) - USD ($)	Total	Accumulated Deficit	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Series A Redeemable Convertible Preferred Units	Series B Redeemable Convertible Preferred Units	Series C Redeemable Convertible Preferred Units	Series A,B and C Convertible Preferred Shares	Common Units Member Units	Common Shares	Incentive Units Member Units
Balance at Dec. 31, 2017					$ 19,768,025	$ 41,712,407
Balance, Units/Shares at Dec. 31, 2017					22,463,665	24,977,489
Balance at Dec. 31, 2017	$ (61,234,562)	$ (62,417,397)		$ (9,751)					$ 6,167		$ 1,186,419
Balance, Units at Dec. 31, 2017									1,897,544		11,927,381
Incentive unit-based compensation	6,189,011										$ 6,189,011
Incentive unit-based compensation, Units/Shares											5,424,605
Exercise of Series A redeemable convertible preferred warrant					$ 319,667
Exercise of Series A redeemable convertible preferred warrant, Units					110,116
Issuance of Series C redeemable convertible preferred units							$ 55,000,001
Issuance of Series C redeemable convertible preferred units, Units							16,467,066
Change in redemption value of redeemable convertible preferred units	(198,366,756)	(198,366,756)			$ 91,044,716	$ 81,253,577	$ 26,068,463
Net loss	(25,392,600)	(25,392,600)
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares					$ (111,132,408)	$ (122,965,984)	$ (81,068,464)	$ 315,166,856
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares, Units/Shares					(22,573,781)	(24,977,489)	(16,467,066)	64,018,336
Conversion of common and incentive units to common and restricted stock			$ 7,377,913						$ (6,167)	$ 3,684	$ (7,375,430)
Conversion of common and incentive units to common and restricted stock, Units/Shares									(1,897,544)	3,683,639	(17,351,986)
Unrealized gain (loss) on available-for-sale securities	(37,472)			(37,472)
Balance at Sep. 30, 2018								$ 315,166,856
Balance, Units/Shares at Sep. 30, 2018								64,018,336
Balance at Sep. 30, 2018	(278,842,379)	(286,176,753)	7,377,913	(47,223)						$ 3,684
Balance, Units at Sep. 30, 2018										3,683,639
Balance at Jun. 30, 2018					$ 65,818,538	$ 79,178,640	$ 57,799,402
Balance, Units/Shares at Jun. 30, 2018					22,463,665	24,977,489	16,467,066
Balance at Jun. 30, 2018	(158,515,897)	(160,738,472)		(96,614)					$ 6,167		$ 2,313,022
Balance, Units at Jun. 30, 2018									1,897,544		17,315,339
Incentive unit-based compensation	5,062,408										$ 5,062,408
Incentive unit-based compensation, Units/Shares											36,647
Exercise of Series A redeemable convertible preferred warrant					$ 319,667
Exercise of Series A redeemable convertible preferred warrant, Units					110,116
Change in redemption value of redeemable convertible preferred units	(112,050,609)	(112,050,609)			$ 44,994,203	$ 43,787,344	$ 23,269,062
Net loss	(13,387,672)	(13,387,672)
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares					$ (111,132,408)	$ (122,965,984)	$ (81,068,464)	$ 315,166,856
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares, Units/Shares					(22,573,781)	(24,977,489)	(16,467,066)	64,018,336
Conversion of common and incentive units to common and restricted stock			7,377,913						$ (6,167)	$ 3,684	$ (7,375,430)
Conversion of common and incentive units to common and restricted stock, Units/Shares									(1,897,544)	3,683,639	(17,351,986)
Unrealized gain (loss) on available-for-sale securities	49,391			49,391
Balance at Sep. 30, 2018								$ 315,166,856
Balance, Units/Shares at Sep. 30, 2018								64,018,336
Balance at Sep. 30, 2018	$ (278,842,379)	(286,176,753)	7,377,913	(47,223)						$ 3,684
Balance, Units at Sep. 30, 2018										3,683,639
Balance, Units/Shares at Oct. 01, 2018	0
Balance at Dec. 31, 2018	$ 136,666,983	(302,264,619)	439,118,089	(217,723)						$ 31,236
Balance, Units at Dec. 31, 2018										31,235,458
Stock-based compensation	15,091,269		15,091,269
Issuance of common stock	29,454,033		29,452,687							$ 1,346
Stock Issued During Period, Shares, New Issues										1,346,313
Net loss	(49,244,511)	(49,244,511)
Restricted stock vesting			(383)							$ 383
Restricted stock vesting, Shares										383,695
Proceeds from exercise of stock options	1,777,456		1,777,345							$ 111
Proceeds from exercise of stock options, Shares										111,091
Unrealized gain (loss) on available-for-sale securities	414,368			414,368
Balance at Sep. 30, 2019	134,159,598	(351,509,130)	485,439,007	196,645						$ 33,076
Balance, Units at Sep. 30, 2019										33,076,557
Balance at Jun. 30, 2019	116,505,261	(333,833,757)	450,007,344	300,150						$ 31,524
Balance, Units at Jun. 30, 2019										31,523,474
Stock-based compensation	4,601,214		4,601,214
Issuance of common stock	29,454,033		29,452,687							$ 1,346
Stock Issued During Period, Shares, New Issues										1,346,313
Net loss	(17,675,373)	(17,675,373)
Restricted stock vesting			(120)							$ 120
Restricted stock vesting, Shares										120,647
Proceeds from exercise of stock options	1,377,968		1,377,882							$ 86
Proceeds from exercise of stock options, Shares										86,123
Unrealized gain (loss) on available-for-sale securities	(103,505)			(103,505)
Balance at Sep. 30, 2019	$ 134,159,598	$ (351,509,130)	$ 485,439,007	$ 196,645						$ 33,076
Balance, Units at Sep. 30, 2019										33,076,557