Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	IPO	Convertible Preferred Stock	Common Stock	Common Stock IPO	Additional Paid-in Capital	Additional Paid-in Capital IPO	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ (142,542)			$ 1		$ 1,558		$ 26	$ (144,127)
Beginning balance (in shares) at Dec. 31, 2019			106,890,000
Beginning balance at Dec. 31, 2019			$ 417,359
Beginning balance (in shares) at Dec. 31, 2019				10,003,000
Vesting of restricted stock (in shares)				1,427,000
Exercise of stock options	2					2
Exercise of stock options (in shares)				2,000
Stock-based compensation expense	755					755
Unrealized gain (loss) on marketable securities, net	(10)							(10)
Net loss	(32,875)								(32,875)
Ending balance at Mar. 31, 2020	(174,670)			$ 1		2,315		16	(177,002)
Ending balance (in shares) at Mar. 31, 2020			106,890,000
Ending balance at Mar. 31, 2020			$ 417,359
Ending balance (in shares) at Mar. 31, 2020				11,432,000
Beginning balance at Dec. 31, 2020	$ (421,184)			$ 2		8,216		30	(429,432)
Beginning balance (in shares) at Dec. 31, 2020	134,113,000		134,113,000
Beginning balance at Dec. 31, 2020	$ 852,897		$ 852,897
Beginning balance (in shares) at Dec. 31, 2020	16,170,000			16,170,000
Conversion of convertible preferred stock into common stock, upon initial public offering	$ 852,897			$ 13		852,884
Conversion of convertible preferred stock into common stock, upon initial public offering (in shares)			(134,113,000)
Conversion of convertible preferred stock into common stock, upon initial public offering			$ (852,897)
Conversion of convertible preferred stock into common stock, upon initial public offering (in shares)				134,113,000
Issuance of common stock in initial public offering, net of offering costs		$ 626,405			$ 3		$ 626,402
Issuance of common stock in initial public offering, net of offering costs (in shares)					27,025,000
Vesting of restricted stock (in shares)				1,428,000
Exercise of stock options	$ 298					298
Exercise of stock options (in shares)	205,000			205,000
Stock-based compensation expense	$ 4,158					4,158
Unrealized gain (loss) on marketable securities, net	26							26
Net loss	(180,617)								(180,617)
Ending balance at Mar. 31, 2021	$ 881,983			$ 18		$ 1,491,958		$ 56	$ (610,049)
Ending balance (in shares) at Mar. 31, 2021	0		0
Ending balance (in shares) at Mar. 31, 2021	178,941,000			178,941,000