Business (Details)						1 Months Ended	3 Months Ended		12 Months Ended
	Mar. 08, 2019 USD ($) $ / shares shares	Mar. 05, 2019 USD ($) $ / shares shares	Aug. 17, 2018 USD ($) $ / shares shares	Aug. 14, 2017 USD ($)	Apr. 27, 2017 USD ($) shares	Aug. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($) shares	Dec. 31, 2018 USD ($) product shares	Dec. 31, 2017 USD ($) shares
Subsequent Event [Line Items]
Number of marketed medical devices | product									1
Revenues									$ 18,326,801	$ 27,813,137
Escrowed cash receivable				$ 3,750,000		$ 3,750,000	$ 0		0	3,752,390
Escrow period				12 months		12 months
Potential future regulatory milestone payment						$ 20,000,000
Net (loss) income									(40,052,810)	11,869,823
Cash flows from operations									(3,128,102)	12,578,778
Accumulated deficit							(98,218,070)		(98,218,070)	(58,165,260)
Cash and cash equivalents							10,646,301		10,646,301	2,472,187
Proceeds from issuance of Series B convertible preferred stock upon warrant exercise, net									$ 5,685,038	0
2 Neurological Clinical And Preclinical Stage Compounds
Subsequent Event [Line Items]
Number of products in development | product									2
3 Preclinical Therapies
Subsequent Event [Line Items]
Number of products in development | product									3
Preclinical Pediatric Orphan Rare Disease Compound
Subsequent Event [Line Items]
Number of products in development | product									1
License and other revenue
Subsequent Event [Line Items]
Revenues				$ 25,000,000		$ 25,000,000			$ 0	$ 25,000,000
Private Placement
Subsequent Event [Line Items]
Proceeds from issuance or sale of equity			$ 3,900,000		$ 4,650,000			$ 3,900,000
Proceeds from issuance of Series B convertible preferred stock upon warrant exercise, net							$ 5,700,000
Sale of stock price per share (in dollars per share) | $ / shares			$ 3.91
Common stock
Subsequent Event [Line Items]
Issuance of stock (in shares) | shares									2,349,968	2,301,598
Common stock | Private Placement
Subsequent Event [Line Items]
Issuance of stock (in shares) | shares			1,000,000		2,345,714			1,000,000
Subsequent Event | Bought Deal
Subsequent Event [Line Items]
Number of shares issued (in shares) | shares	1,818,182	1,818,182
Sale of stock price per share (in dollars per share) | $ / shares	$ 5.50	$ 5.50
Consideration received	$ 9,000,000	$ 9,000,000
Armistice | Subsequent Event | Bought Deal
Subsequent Event [Line Items]
Number of shares issued (in shares) | shares	363,637	363,637