Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Related party, receivable from collaboration partners	$ 4,924	$ 943
Related party, deferred revenue - current	67,571	67,571
Related party, deferred revenue - noncurrent	110,097	117,808
Related party, other long-term liabilities	$ 9,703	$ 9,703
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	70,965,513	65,114,685
Common stock, shares outstanding	70,965,513	65,114,685