Investments - Schedule of Available-for-sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Total	$ 47,415	$ 100,389
Gross Unrealized Gains	39	2
Gross Unrealized Losses	(17)	(173)
Fair Value	47,437	100,218
Certificates of deposit
Investment [Line Items]
Total	5,646	10,787
Gross Unrealized Gains	17	0
Gross Unrealized Losses	0	0
Fair Value	5,663	10,787
US Treasury securities
Investment [Line Items]
Total	12,564	22,185
Gross Unrealized Gains	16	1
Gross Unrealized Losses	(1)	(66)
Fair Value	12,579	22,120
US Agency securities
Investment [Line Items]
Total	4,002	8,024
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(4)	(45)
Fair Value	3,998	7,980
Commercial paper
Investment [Line Items]
Total	2,492	17,025
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	0
Fair Value	2,491	17,025
Asset-backed securities
Investment [Line Items]
Total		12,007
Gross Unrealized Gains		0
Gross Unrealized Losses		(9)
Fair Value		11,998
Corporate notes and bonds
Investment [Line Items]
Total	22,711	30,361
Gross Unrealized Gains	6	0
Gross Unrealized Losses	(11)	(53)
Fair Value	$ 22,706	$ 30,308

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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