Investments - Summary of Short term Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 394,271	$ 275,801
Gross Unrealized Gains	27	48
Gross Unrealized Losses	(42)	(23)
Total Fair Value	394,256	275,826
Within 1 year, Amortized Cost	379,754
After 1 year through 5 years, Amortized Cost	11,067
After 5 years through 10 Years, Amortized Cost	3,450
Within 1 year, Fair Value	379,731
After 1 year through 5 years, Fair Value	11,078
After 5 years through 10 years, Fair Value	3,447
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	159,084	129,098
Gross Unrealized Gains	27	48
Gross Unrealized Losses	(37)	(23)
Total Fair Value	159,074	129,123
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,607	19,111
Gross Unrealized Gains	14	18
Gross Unrealized Losses	(7)	(9)
Total Fair Value	16,614	19,120
Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,178	5,046
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total Fair Value	10,178	5,046
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	24,023	15,148
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total Fair Value	24,023	15,148
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	59,953	50,771
Gross Unrealized Gains	1	16
Gross Unrealized Losses	(27)	(12)
Total Fair Value	59,927	50,775
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	18,547	12,702
Gross Unrealized Gains	8	8
Gross Unrealized Losses	(3)	(2)
Total Fair Value	18,552	12,708
U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,585	8,415
Gross Unrealized Gains	0	3
Gross Unrealized Losses	0	0
Total Fair Value	1,585	8,418
U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	27,891	17,605
Gross Unrealized Gains	4	3
Gross Unrealized Losses	0	0
Total Fair Value	27,895	17,608
Variable rate demand notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	300	300
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total Fair Value	300	300
Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	235,187	146,703
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(5)	0
Total Fair Value	235,182	146,703
Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	901	976
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total Fair Value	901	976
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	11,572	5,293
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total Fair Value	11,572	5,293
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,964	1,744
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(5)	0
Total Fair Value	8,959	1,744
Money market funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	211,723	138,290
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total Fair Value	211,723	138,290
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,777	400
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total Fair Value	1,777	400
U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	250
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Total Fair Value	250
Level 1
Debt Securities, Available-for-sale [Line Items]
Total	250,947	161,920
Level 1 | Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	38,073	22,654
Level 1 | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 1 | Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	10,178	5,046
Level 1 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 1 | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 1 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 1 | U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 1 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	27,895	17,608
Level 1 | Variable rate demand notes
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 1 | Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	212,874	139,266
Level 1 | Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	901	976
Level 1 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 1 | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 1 | Money market funds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	211,723	138,290
Level 1 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 2
Debt Securities, Available-for-sale [Line Items]
Total	143,309	113,906
Level 2 | Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	121,001	106,469
Level 2 | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	16,614	19,120
Level 2 | Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 2 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	24,023	15,148
Level 2 | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	59,927	50,775
Level 2 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	18,552	12,708
Level 2 | U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	1,585	8,418
Level 2 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 2 | Variable rate demand notes
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	300	300
Level 2 | Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	22,308	7,437
Level 2 | Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 2 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	11,572	5,293
Level 2 | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	8,959	1,744
Level 2 | Money market funds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	0	0
Level 2 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	1,777	$ 400
Level 2 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value	$ 0