Investments and Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Investments and Fair Value of Financial Assets and Liabilities

Schedule of investments by security type

Investments by security type consisted of the following (in thousands):

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. treasury bills and notes (due within one year)	$	189,816	$	91	$	(20)	$	189,887
U.S. government agency bonds (due within one year)		1,498		4		—		1,502
	$	191,314	$	95	$	(20)	$	191,389

	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. treasury notes (due within one year)	$	79,312	$	—	$	(26)	$	79,286
U.S. government agency bonds (due within one year)		17,704		—		(3)		17,701
	$	97,016	$	—	$	(29)	$	96,987

Schedule of financial assets and liabilities measured at fair value on a recurring basis

The following tables present the Company’s fair value hierarchy for its assets and liabilities, which are measured at fair value on a recurring basis (in thousands):

	Fair value measurements at December 31, 2019 using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	91,898	$	—	$	—	$	91,898
Investments:
U.S. government agency bonds		—		1,502		—		1,502
U.S. treasury bills and notes		—		189,887		—		189,887
	$	91,898	$	191,389	$	—	$	283,287

	Fair value measurements at December 31, 2018 using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	282,160	$	—	$	—	$	282,160
U.S. treasury bills		—		24,904		—		24,904
Investments:
U.S. government agency bonds		—		17,701		—		17,701
U.S. treasury notes		—		79,286		—		79,286
	$	282,160	$	121,891	$	—	$	404,051