Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring basis - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financial assets
Total financial assets	$ 722,658	$ 786,641
Level 1
Financial assets
Total financial assets	151,330	103,283
Level 2
Financial assets
Total financial assets	571,328	683,358
Money Market Funds
Financial assets
Total financial assets	151,330	103,283
Money Market Funds | Level 1
Financial assets
Total financial assets	151,330	103,283
U.S. Government Debt Securities
Financial assets
Total financial assets	559,788	671,777
U.S. Government Debt Securities | Level 2
Financial assets
Total financial assets	559,788	671,777
Corporate Bonds
Financial assets
Total financial assets	11,540	11,581
Corporate Bonds | Level 2
Financial assets
Total financial assets	$ 11,540	$ 11,581