Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		9 Months Ended
	Aug. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Class of Stock [Line Items]
Proceeds from issuance of common stock, net of issuance costs		$ 271,500	$ 62,870	$ 328,789
Share of common stock issued		7,187,500
Option To Purchase Additional Shares
Class of Stock [Line Items]
Share of common stock issued		937,500
Cersci Therapeutics
Class of Stock [Line Items]
Stock issued in connection with acquisition, shares	1,200,000
Issuance of common stock in connection with merger agreement	$ 44,300