Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	$ 99,915	$ 331,549
Marketable securities:
Unrealized gains	476	7
Unrealized losses	(8)	(39)
Cost	633,663	358,806
Fair value	634,131	358,774
Corporate debt securities due within 1 year of date of purchase
Marketable securities:
Cost	382,028	27,257
Unrealized gains	195	7
Unrealized losses	(7)	(39)
Fair value	382,216	27,225
US government and government sponsored entities due within 1 year of date of purchase (Level 2)
Marketable securities:
Cost	150,743
Unrealized gains	280
Unrealized losses	(1)
Fair value	151,022
Cash
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	2,729	15,100
Money market funds
Cash, Cash Equivalents and Marketable Securities
Cash and cash equivalents	$ 78,555	$ 316,449