Cash Equivalents and Marketable Securities - Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	$ 318,713	$ 304,142
Total cash equivalents and marketable securities, Gross Unrealized Gains		12
Total cash equivalents and marketable securities, Gross Unrealized Losses	(143)	(10)
Total cash equivalents and marketable securities, Fair Value	318,570	304,144
U.S. Treasury and agency securities
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	40,093	183,203
Total cash equivalents and marketable securities, Gross Unrealized Gains		10
Total cash equivalents and marketable securities, Gross Unrealized Losses	(76)	(3)
Total cash equivalents and marketable securities, Fair Value	40,017	183,210
Corporate debt securities
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	75,598	27,592
Total cash equivalents and marketable securities, Gross Unrealized Gains		2
Total cash equivalents and marketable securities, Gross Unrealized Losses	(50)	(4)
Total cash equivalents and marketable securities, Fair Value	75,548	27,590
Supranational and sovereign government securities
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	6,011
Total cash equivalents and marketable securities, Gross Unrealized Losses	(1)
Total cash equivalents and marketable securities, Fair Value	6,010
Money Market Funds
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	39,854	27,481
Total cash equivalents and marketable securities, Fair Value	39,854	27,481
Commercial Paper
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	157,157	65,866
Total cash equivalents and marketable securities, Gross Unrealized Losses	(16)	(3)
Total cash equivalents and marketable securities, Fair Value	$ 157,141	$ 65,863