Stockholder's Equity - Public Offering Narrative (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Apr. 15, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Series B issuance, net of issuance costs (in shares)	12,000,000
Sales of stock, price per share (in usd per share)	$ 5.00
Sale of stock, number of shares issued in transaction (in shares)	10,000,000
Proceeds from issuance of common stock before underwriting discounts, commissions, and other expenses	$ 50,000
Proceeds from issuance of common stock after underwriting discounts, commissions, and other expenses	47,600
Proceeds from issuance of common stock, less underwriters discount	$ 19,000	$ 0	$ 48,000	$ 0
IPO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted to underwriters (in shares)	1,800,000