Fair Value Measurements, Cash Equivalents and Marketable Securities - Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Debt Securities, Available-for-sale [Line Items]
Amortization cost, cash and cash equivalents	$ 933,694		$ 271,073
Amortized cost, cash and cash equivalents and debt securities available-for-sale	1,001,068	$ 1,067,608
Gross Unrealized Gain	2	0
Gross Unrealized Loss	(3)	(11)
Estimated fair value, cash, cash equivalents and debt securities	1,001,067	1,067,597
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortization cost, cash and cash equivalents	15,061	1,032,500
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Estimated fair value, cash and cash equivalents	15,061	1,032,500
Fixed income bond funds
Debt Securities, Available-for-sale [Line Items]
Amortized cost, debt securities, available-for-sale	101,115
Gross Unrealized Gain	0
Gross Unrealized Loss	0
Estimated fair value, debt securities	101,115
U.S. government debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost, debt securities, available-for-sale	884,892	35,108
Gross Unrealized Gain	2	0
Gross Unrealized Loss	(3)	(11)
Estimated fair value, debt securities	$ 884,891	$ 35,097