Available-for-Sale Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2020

Investments Debt And Equity Securities [Abstract]

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

The following tables summarize the Company’s available-for-sale marketable securities by major type of security as of March 31, 2020 and December 31, 2019:

As of March 31, 2020

			Gross Unrealized				Estimated Fair
Type of Security	Amortized Cost		Gains		Losses		Value
U.S. Treasury securities	$	16,065	$	249	$	—	$	16,314
U.S. government agency obligations		17,601		39		(1)		17,639
Corporate bonds		93,681		79		(460)		93,300
Commercial paper		31,949		26		—		31,975
Municipal bonds		3,500		—		—		3,500
Total available-for-sale marketable securities	$	162,796	$	393	$	(461)	$	162,728

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

The following tables summarize the fair value and gross unrealized losses of the Company’s available-for-sale marketable securities by investment category and disaggregated by the length of time that individual debt securities have been in a continuous unrealized loss position.

As of March 31, 2020

	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. government agency obligations	$	4,248	$	(1)	$	—	$	—	$	4,248	$	(1)
Corporate bonds		63,046		(460)		—		—		63,046		(460)
Total	$	67,294	$	(461)	$	—	$	—	$	67,294	$	(461)

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

The Company classifies its marketable debt securities based on their contractual maturity dates. As of March 31, 2020, the Company’s marketable debt securities mature at various dates through December 2021. The amortized cost and fair values of marketable debt securities by contractual maturity were as follows.

	As of March 31, 2020				As of December 31, 2019
Contractual maturity	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than one year	$	103,142	$	103,160	$	136,565	$	136,701
One year to two years		59,654		59,568		63,125		63,159
Total	$	162,796	$	162,728	$	199,690	$	199,860