Fair Value Measurement (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Marketable securities
Marketable securities	$ 177,089	$ 190,199
Money market funds
Marketable securities
Marketable securities	29,402	45,948
U.S. treasury securities
Marketable securities
Marketable securities	84,779	74,776
Corporate bonds
Marketable securities
Marketable securities	12,942	8,938
Commercial paper
Marketable securities
Marketable securities	49,966	60,537
Level 1
Marketable securities
Marketable securities	114,181	120,724
Level 1 | Money market funds
Marketable securities
Marketable securities	29,402	45,948
Level 1 | U.S. treasury securities
Marketable securities
Marketable securities	84,779	74,776
Level 1 | Corporate bonds
Marketable securities
Marketable securities	0	0
Level 1 | Commercial paper
Marketable securities
Marketable securities	0	0
Level 2
Marketable securities
Marketable securities	62,908	69,475
Level 2 | Money market funds
Marketable securities
Marketable securities	0	0
Level 2 | U.S. treasury securities
Marketable securities
Marketable securities	0	0
Level 2 | Corporate bonds
Marketable securities
Marketable securities	12,942	8,938
Level 2 | Commercial paper
Marketable securities
Marketable securities	49,966	60,537
Level 3
Marketable securities
Marketable securities	0	0
Level 3 | Money market funds
Marketable securities
Marketable securities	0	0
Level 3 | U.S. treasury securities
Marketable securities
Marketable securities	0	0
Level 3 | Corporate bonds
Marketable securities
Marketable securities	0	0
Level 3 | Commercial paper
Marketable securities
Marketable securities	$ 0	$ 0