Nature of Business and Basis of Presentation - Additional Information (Details) $ / shares in Units, $ in Thousands			12 Months Ended
	Apr. 02, 2018 USD ($) $ / shares shares	Mar. 16, 2018	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	May 14, 2018 shares
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Net loss | $			$ 57,215	$ 29,991
Accumulated deficit | $			$ 97,396	$ 40,181
Reverse stock split ratio of issued and outstanding shares of common stock			one-for-5.263
Reverse stock split ratio of issued and outstanding shares of common stock, conversion		5.263
Reverse stock split effective date			Mar. 16, 2018
Convertible preferred shares converted to common stock	24,168,656
Preferred stock outstanding			0	0
Initial Public Offering
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Shares issued and sold	10,350,000
Common stock at a public offering price | $ / shares	$ 16.00
Proceeds from issuance of common stock | $	$ 165,600
Preferred stock outstanding					0