Organization - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Entity incorporation date		Jul. 05, 2016
Net proceeds received from offering		$ 90,908
Common stock, shares authorized	150,000,000	150,000,000	30,000,000
Preferred stock, shares authorized	10,000,000	10,000,000	0
Accumulated deficit		$ 71,393	$ 33,779
Initial Public Offering
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of common stock shares sold	6,516,667
Issuance price per shares	$ 15.00
Net proceeds received from offering	$ 89,400
Deferred offering costs			$ 900
Convertible preferred stock converted into common stock	15,870,559
Over-allotment Option
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of common stock shares sold	850,000