Investments - Amortized Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Cost	$ 586,552	$ 419,783
Gross Unrealized Gains	3	14
Gross Unrealized Losses	(4,559)	(922)
Fair Value	581,996	418,875
Included in cash and cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cost	80,201	950
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(28)	0
Fair Value	80,175	950
Included in marketable securities
Debt Securities, Available-for-sale [Line Items]
Cost	506,351	418,833
Gross Unrealized Gains	1	14
Gross Unrealized Losses	(4,531)	(922)
Fair Value	501,821	417,925
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Cost	251,673	161,938
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(2,685)	(474)
Fair Value	248,989	161,465
U.S. agency and government sponsored securities
Debt Securities, Available-for-sale [Line Items]
Cost	4,996	4,995
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(89)	(25)
Fair Value	4,907	4,970
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cost	130,103	40,788
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(126)	(4)
Fair Value	129,978	40,784
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Cost	158,595	165,522
Gross Unrealized Gains	1	13
Gross Unrealized Losses	(1,348)	(345)
Fair Value	157,248	165,190
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cost	41,185	46,540
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(311)	(74)
Fair Value	$ 40,874	$ 46,466