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

9 Months Ended

Sep. 30, 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):

	September 30, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. treasury bills and notes (due within one year)	$	201,045	$	165	$	(8)	$	201,202
U.S. government agency bonds (due within one year)		13,867		9		—		13,876
	$	214,912	$	174	$	(8)	$	215,078

	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 September 30, 2019 using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	109,611	$	—	$	—	$	109,611
Investments:
U.S. government agency bonds		—		13,876		—		13,876
U.S. treasury bills and notes		—		201,202		—		201,202
	$	109,611	$	215,078	$	—	$	324,689

	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