Organization - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended
	Jan. 30, 2018	Jan. 12, 2018	Jun. 30, 2018	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Entity incorporation date			Jul. 05, 2016
Reverse stock split effective date		Jan. 12, 2018
Reverse stock split description		one-for-1.2804	one-for-1.2804
Net proceeds received from offering			$ 89,938
Common stock, shares authorized			150,000,000	30,000,000
Preferred stock, shares authorized			10,000,000	0
Accumulated deficit			$ 57,229	$ 33,779
Cash, cash equivalents and marketable securities			$ 125,900
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
Payments for initial public offering after deducting underwriting discounts and commissions and other offering expenses	$ 8,400
Convertible preferred stock converted into common stock	15,870,559
Common stock, shares authorized	150,000,000
Preferred stock, shares authorized	10,000,000
Over-allotment Option
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of common stock shares sold	850,000