Fair Value Measurements, Cash Equivalents and Marketable Securities - Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortization cost, cash and cash equivalents	$ 1,029,027		$ 223,640
Amortized cost, cash and cash equivalents and debt securities available-for-sale	1,067,288	$ 1,067,608
Gross Unrealized Gain	2	0
Gross Unrealized Loss	0	(11)
Cash, cash equivalents and debt securities, fair value	1,067,290	1,067,597
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortization cost, cash and cash equivalents	638,715	1,032,500
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Estimated fair value, cash and cash equivalents	638,715	1,032,500
Fixed income bond funds
Debt Securities, Available-for-sale [Line Items]
Amortized cost, debt securities, available-for-sale	100,080
Gross Unrealized Gain	0
Gross Unrealized Loss	0
Estimated fair value, debt securities	100,080
U.S. government debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost, debt securities, available-for-sale	328,493	35,108
Gross Unrealized Gain	2	0
Gross Unrealized Loss	0	(11)
Estimated fair value, debt securities	$ 328,495	$ 35,097