Fair Value Measurements - Financial Assets Measured at Fair Value on a Recurring Basis by Level Within Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2022		Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	$ 2,403,183		$ 764,540
Financial Assets, Gross Unrealized Holding Gains	0		0
Financial Assets, Gross Unrealized Holding Losses	(8,396)		(872)
Financial Assets, Aggregate Fair Value	2,394,787		763,668
Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	909,342	[1]	345,098	[2]
Financial Assets, Gross Unrealized Holding Gains	0	[1]	0	[2]
Financial Assets, Gross Unrealized Holding Losses	0	[1]	0	[2]
Financial Assets, Aggregate Fair Value	909,342	[1]	345,098	[2]
Level 2 | U.S. Government Treasuries
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	1,493,841		419,442
Financial Assets, Gross Unrealized Holding Gains	0		0
Financial Assets, Gross Unrealized Holding Losses	(8,396)		(872)
Financial Assets, Aggregate Fair Value	$ 1,485,445		$ 418,570

[1] Includes $19.3 million of restricted cash equivalents.

[2] Includes $15.6 million of restricted cash equivalents.