Available-for-Sale Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2020

Investments Debt And Equity Securities [Abstract]

Summary of Available-for-Sale Marketable Securities by Major Type of Security

As of September 30, 2020

			Gross Unrealized				Estimated Fair
Type of Security	Amortized Cost		Gains		Losses		Value
U.S. Treasury securities	$	9,081	$	98	$	—	$	9,179
U.S. government agency obligations		3,499		8		—		3,507
Corporate bonds		41,827		256		—		42,083
Commercial paper		1,324		1		—		1,325
Total available-for-sale marketable securities	$	55,731	$	363	$	—	$	56,094

As of December 31, 2019

			Gross Unrealized				Estimated Fair
Type of Security	Amortized Cost		Gains		Losses		Value
U.S. Treasury securities	$	16,052	$	31	$	(2)	$	16,081
U.S. government agency obligations		25,803		14		(1)		25,816
Corporate bonds		115,788		125		(23)		115,890
Commercial paper		38,547		27		(1)		38,573
Municipal bonds		3,500		—		—		3,500
Total available-for-sale marketable securities	$	199,690	$	197	$	(27)	$	199,860

Schedule of Fair Values and Continuous Unrealized Loss Positions of Available-for-Sale Marketable Securities

As of December 31, 2019

	Less than 12 Months				12 Months or Greater				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury securities	$	3,185	$	(2)	$	—	$	—	$	3,185	$	(2)
U.S. government agency obligations		2,400		(1)		—		—		2,400		(1)
Corporate bonds		28,895		(23)		—		—		28,895		(23)
Commercial paper		4,264		(1)		—		—		4,264		(1)
Total	$	38,744	$	(27)	$	—	$	—	$	38,744	$	(27)

Schedule of Amortized Cost and Fair Values of Marketable Debt Securities by Contractual Maturity

	As of September 30, 2020				As of December 31, 2019
Contractual maturity	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than one year	$	45,331	$	45,588	$	136,565	$	136,701
One year to two years		10,400		10,506		63,125		63,159
Total	$	55,731	$	56,094	$	199,690	$	199,860