Significant Risks and Uncertainties - Additional Information (Details)		1 Months Ended	12 Months Ended
	Jun. 21, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) Distributor shares	Dec. 31, 2017 USD ($)
Risks And Uncertainties [Line Items]
Working capital			$ 65,600,000	$ 32,900,000
Proceeds from issuance of common stock net of underwriting discount and other offering expenses			$ 78,334,457
Number of specialty pharmaceutical distributor | Distributor			1
Specialty Pharmaceutical Distributor In United States
Risks And Uncertainties [Line Items]
Accounts receivable			$ 195,730	$ 31,740
Common Stock
Risks And Uncertainties [Line Items]
Common stock, shares issued | shares			5,980,000
IPO
Risks And Uncertainties [Line Items]
Proceeds from issuance of common stock net of underwriting discount and other offering expenses	$ 77,500,000	$ 77,500,000
IPO | Common Stock
Risks And Uncertainties [Line Items]
Common stock, shares issued | shares	5,980,000	5,980,000
Common stock, issue price per share | $ / shares	$ 15.00	$ 15.00