Organization and Description of Business - Additional Information (Details) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Oct. 22, 2018 USD ($) $ / shares shares	Oct. 31, 2018	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares
Organization and Description of Business [Line Item]
Proceeds from issuance of common stock in initial public offering, net | $			$ 42,974
Common stock, shares authorized			200,000,000	14,918,087
Common stock, par value | $ / shares			$ 0.001	$ 0.001
Preferred Stock, Shares Authorized			10,000,000	0
Preferred Stock, Par Value | $ / shares			$ 0.001	$ 0.001
Reverse stock split description			The Company effected a 11.0634-for-1 reverse split of its outstanding common stock and redeemable convertible preferred stock.
Accumulated deficit | $			$ (122,911)	$ (99,065)
Cash and cash equivalents | $			61,031	$ 13,406
Working capital | $			$ 58,100
Common Stock
Organization and Description of Business [Line Item]
Common stock, shares, issued and sold			9,864,666
Conversion of redeemable convertible preferred stock into common stock, shares			13,225,048
Reverse stock split conversion ratio		11.0634
Initial Public Offering
Organization and Description of Business [Line Item]
Common stock, shares, issued and sold	9,864,666
Common stock,public offering price | $ / shares	$ 5.00
Proceeds from issuance of common stock in initial public offering, net | $	$ 43,000
Conversion of redeemable convertible preferred stock into common stock, shares	13,200,115
Common stock, shares authorized			200,000,000
Common stock, par value | $ / shares			$ 0.001
Preferred Stock, Shares Authorized			10,000,000
Preferred Stock, Par Value | $ / shares			$ 0.001
Initial Public Offering | Common Stock
Organization and Description of Business [Line Item]
Conversion of redeemable convertible preferred stock into common stock, shares	13,200,115