Fair Value Measurements - Financial Assets Measured at Fair Value on a Recurring Basis by Level Within Fair Value Hierarchy (Details) - USD ($) $ in Thousands		Jun. 30, 2022		Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost		$ 2,263,142		$ 764,540
Financial Assets, Gross Unrealized Holding Gains		0		0
Financial Assets, Gross Unrealized Holding Losses		(7,307)		(872)
Financial Assets, Aggregate Fair Value		2,255,835		763,668
Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost		1,503,130	[1]	345,098	[2]
Financial Assets, Gross Unrealized Holding Gains	[1]	0
Financial Assets, Gross Unrealized Holding Losses	[1]	0
Financial Assets, Aggregate Fair Value		1,503,130	[1]	345,098	[2]
Level 1 | U.S. Government Treasuries
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Gross Unrealized Holding Gains	[2]			0
Financial Assets, Gross Unrealized Holding Losses	[2]			0
Level 2 | U.S. Government Treasuries
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost		760,012		419,442
Financial Assets, Gross Unrealized Holding Gains		0		0
Financial Assets, Gross Unrealized Holding Losses		(7,307)		(872)
Financial Assets, Aggregate Fair Value		$ 752,705		$ 418,570

[1] Includes $21.5 million of restricted cash equivalents.

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