Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Cash and cash equivalents:
Amortized cost	$ 37,187	$ 151,570
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Fair value	37,187	151,570
Investments:
Amortized cost	102,740	88,846
Gross unrealized gains	0	8
Gross unrealized losses	(126)	(60)
Total investments	102,614	88,794
Total cash, cash equivalents and investments, amortized cost	139,927	240,416
Total cash, cash equivalents and investments, Gross Unrealized Gains	0	8
Total cash, cash equivalents and investments, Gross Unrealized Losses	(126)	(60)
Total cash, cash equivalents and investments, fair value	139,801	240,364
Cash and cash equivalents
Cash and cash equivalents:
Amortized cost	37,187	151,570
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Fair value	37,187	151,570
Certificates of deposit (due within 1 year)
Investments:
Amortized cost	9,047
Gross unrealized gains	0
Gross unrealized losses	(9)
Total investments	9,038
Commercial paper (due within 1 year)
Investments:
Amortized cost	50,975	44,122
Gross unrealized gains	0	5
Gross unrealized losses	(55)	(23)
Total investments	50,920	44,104
Corporate bonds (due within 1 year)
Investments:
Amortized cost	42,718	44,724
Gross unrealized gains	0	3
Gross unrealized losses	(62)	(37)
Total investments	42,656	$ 44,690
U.S. Government and government agencies (due within 1 year)
Investments:
Amortized cost
Gross unrealized gains	0
Gross unrealized losses
Total investments	$ 0