Investments - Summary of Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Cash and cash equivalents:
AMORTIZED COST	$ 122,695	$ 151,570	$ 134,179	$ 143,940
GROSS UNREALIZED GAINS	0	0
GROSS UNREALIZED LOSSES	0	0
FAIR VALUE	122,695	151,570
Investments:
AMORTIZED COST	85,573	88,846
GROSS UNREALIZED GAINS	1	8
GROSS UNREALIZED LOSSES	(65)	(60)
FAIR VALUE	85,509	88,794
Total cash, cash equivalents and investments, Amortized Cost	208,268	240,416
Total cash, cash equivalents and investments, Gross Unrealized Gains	1	8
Total cash, cash equivalents and investments, Gross Unrealized Losses	(65)	(60)
Total cash, cash equivalents and investments, Fair Value	208,204	240,364
Cash and cash equivalents
Cash and cash equivalents:
AMORTIZED COST	122,695	151,570
GROSS UNREALIZED GAINS		0
GROSS UNREALIZED LOSSES		0
FAIR VALUE	122,695	151,570
Commercial paper (due within 1 year)
Investments:
AMORTIZED COST	42,942	44,122
GROSS UNREALIZED GAINS	1	5
GROSS UNREALIZED LOSSES	(41)	(23)
FAIR VALUE	42,902	44,104
Corporate bonds (due within 1 year)
Investments:
AMORTIZED COST	42,631	44,724
GROSS UNREALIZED GAINS	0	3
GROSS UNREALIZED LOSSES	(24)	(37)
FAIR VALUE	$ 42,607	$ 44,690