Fair Value of Financial Assets and Liability (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value of Financial Assets and Liability

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

	Fair value Measurements as of
	September 30, 2018 using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash Equivalents:
Corporate Debt Securities and Commercial Paper	$	—	$	—	$	—	$	—
Money Market Funds		57,856		—		—		57,856
Marketable Securities:
Corporate Debt Securities and Commercial Paper		—		214,139		—		214,139
U.S. Treasury Securities		—		—		—		—
Total	$	57,856	$	214,139	$	—	$	271,995

	Fair value Measurements as of
	December 31, 2017 using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash Equivalents:
Corporate Debt Securities	$	—	$	15,104	$	—	$	15,104
Money Market Funds		17,753		—		—		17,753
Marketable Securities:
Corporate Debt Securities		—		96,901		—		96,901
U.S. Treasury Securities		16,945		—		—		16,945
Total	$	34,698	$	112,005	$	—	$	146,703

Schedule of marketable securities

	September 30, 2018
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Assets
Corporate Debt Securities and Commercial Paper (due within 1 year)	$	214,225	$	4	$	(90)	$	214,139
U.S. Treasury Securities (due within 1 year)		—		—		—		—
	$	214,225	$	4	$	(90)	$	214,139

	December 31, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Assets
Corporate Debt Securities (due within 1 year)	$	97,029	$	—	$	(128)	$	96,901
U.S. Treasury Securities (due within 1 year)		16,958		—		(13)		16,945
	$	113,987	$	—	$	(141)	$	113,846

2017 Series A Investor Instrument

Fair Value of Financial Assets and Liability

Schedule of the fair value of financial liabilities

	2017 Series A Investor
	Instrument
Fair value at December 31, 2016	$	—
Fair value upon the January 2017 Initial Closing, net		328
Change in fair value		1,863
Reclassification of liability upon August 2017 Second Tranche Closing		(2,191)
Fair value at September 30, 2017	$	—

Schedule of assumptions and inputs were used in determining fair value using Black Scholes option pricing model

	August 2017 Second Tranche Closing
Series A Convertible Preferred Stock Exercise Price	$	1.00
Series A Convertible Preferred Stock Fair Value	$	1.33
Expected term		1.5 months
Expected volatility		64.0	%
Expected interest rate		0.95	%
Expected dividend yield		—