Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended							12 Months Ended
	Dec. 31, 2020	Oct. 31, 2019	Apr. 30, 2019	Oct. 31, 2018	Aug. 31, 2018	Jul. 31, 2018	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 02, 2018
Subsidiary Sale Of Stock [Line Items]
Common stock, shares authorized	300,000,000							300,000,000	300,000,000
Common stock, par value	$ 0.0001							$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000							10,000,000	10,000,000
Preferred stock, par value	$ 0.0001							$ 0.0001	$ 0.0001
Preferred stock, shares issued	0							0	0
Preferred stock, shares outstanding	0							0	0
Common stock, shares issued	47,552,693							47,552,693	36,332,956
Common stock, shares outstanding	47,552,693							47,552,693	36,332,956
Common stock voting rights								Holders of the Company’s common stock are entitled to one vote per share.
Net proceeds from issuance of stock								$ 10,879,000	$ 75,202,000	$ 92,586,000
Common stock, preferred stock, debt securities, warrants and units covered in Registration Statement		$ 250,000,000.0
Percentage of gross proceeds as underwriter compensation		3.00%
Maximum offering expense agreed to be reimbursed		$ 50,000
Issuance of pre-funded warrants, net of issuance costs								$ 87,704,000
Warrant exercise price	$ 3.34							$ 3.34
Class of warrant issued									0
Warrants exercised								0
Warrants outstanding									$ 0
Maximum [Member]
Subsidiary Sale Of Stock [Line Items]
Net proceeds from issuance of stock		$ 75,000,000.0
Series C Preferred Stock [Member]
Subsidiary Sale Of Stock [Line Items]
Shares issued price per share					$ 13.04	$ 13.04	$ 13.04
Proceed from issuance of stock					$ 10,000,000.0	$ 2,000,000.0	$ 8,900,000
Stock issued, number of shares					768,115	153,360	690,128
Payment for issuance cost							$ 100,000
Amended and Restated Certificate of Incorporation [Member]
Subsidiary Sale Of Stock [Line Items]
Common stock, shares authorized											300,000,000
Common stock, par value											$ 0.0001
Preferred stock, shares authorized											10,000,000
Preferred stock, par value											$ 0.0001
Underwritten Public Offering [Member]
Subsidiary Sale Of Stock [Line Items]
Shares issued price per share			$ 11.50
Net proceeds from issuance of stock			$ 69,700,000
ATM Equity Offering Program [Member]
Subsidiary Sale Of Stock [Line Items]
Stock issued, number of shares								1,160,963	490,880
Payment for issuance cost								$ 100,000	$ 300,000
Net proceeds from issuance of stock								9,800,000	3,800,000
Payment of commissions on sale of shares								$ 300,000	$ 100,000
Common Stock [Member] | IPO [Member]
Subsidiary Sale Of Stock [Line Items]
Shares issued price per share				$ 15.00						$ 15.00
Stock issued, number of shares				6,854,202						6,854,202
Payment for issuance cost										$ 10,276,000
Net proceeds from issuance of stock				$ 92,500,000
Conversion of preferred stock shares into common stock shares				19,409,132
Reclassified common stock and additional paid in capital				$ 177,900,000						$ 14,000
Common Stock [Member] | Over-Allotment Option [Member]
Subsidiary Sale Of Stock [Line Items]
Stock issued, number of shares				187,535
Common Stock [Member] | Underwritten Public Offering [Member]
Subsidiary Sale Of Stock [Line Items]
Stock issued, number of shares			6,500,000
Common Stock [Member] | ATM Equity Offering Program [Member]
Subsidiary Sale Of Stock [Line Items]
Stock issued, number of shares								1,160,963	490,880
Payment for issuance cost								$ 104,000	$ 301,000
Common Stock [Member] | Private Investment in Public Equity [Member]
Subsidiary Sale Of Stock [Line Items]
Shares issued price per share	$ 3.71							$ 3.71
Proceed from issuance of stock	$ 15,000,000.0
Stock issued, number of shares	4,043,127							9,586,478
Payment for issuance cost								$ 1,394,000
Class of warrant issued	0							0
Underwriter placement and legal fees	$ 5,200,000
Common Stock and Warrants [Member] | Private Investment in Public Equity [Member]
Subsidiary Sale Of Stock [Line Items]
Shares issued price per share	$ 3.34							$ 3.34
Proceed from issuance of stock	$ 110,000,000.0
Sale of common stock	5,543,351
Warrant exercise price	$ 0.01							0.01
Offering price per share	$ 3.33							$ 3.33
Warrants to purchase shares of common stock	27,480,719
Maximum percentage of common stock ownership to exercise warrant	9.99%