Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2015

Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):

	September 30, 2015
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	116,642	$	—	$	—	$	116,642
U.S. government and agency securities		—		204,068		—		204,068
Corporate debt securities		—		83,267		—		83,267
Commercial paper		—		38,464		—		38,464
Total	$	116,642	$	325,799	$	—	$	442,441

	December 31, 2014
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	110,001	$	—	$	—	$	110,001
Financial Liabilities:
Convertible preferred stock warrant liability	$	—	$	—	$	100	$	100
Common stock warrant liability		—		—		889		889
Total	$	—	$	—	$	989	$	989

Summary of Changes in Fair Value of Level 3 Financial Liabilities

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands):

	Convertible Preferred Stock Warrant Liability			Common Stock Warrant Liability
Balance at December 31, 2014	$	100		$	889
Net increase in fair value upon remeasurement		1,108			24,969
Reclassification to additional paid-in capital		(1,208	)		(25,858	)
Balance at September 30, 2015	$	—		$	—

Summary of Estimated Value of Cash Equivalents and Marketable Securities and Gross Unrealized Holding Gains and Losses

The following tables summarize the estimated value of our cash equivalents and marketable securities and the gross unrealized holding gains and losses (in thousands):

	September 30, 2015
	Amortized cost		Unrealized gains		Unrealized losses			Estimated Fair Value
Cash and cash equivalents:
Cash	$	5,972	$	—	$	—		$	5,972
Money market funds		116,642		—		—			116,642
Commercial paper		24,998		—		—			24,998
U.S. government and agency securities		23,658		—		—			23,658
Corporate debt securities		9,721		—		—			9,721
Total cash and cash equivalents	$	180,991	$	—	$	—		$	180,991
Marketable securities:
U.S. government and agency securities	$	180,344	$	64	$	—		$	180,408
Corporate debt securities		73,536		36		(25	)		73,547
Commercial paper		13,466		—		—			13,466
Total marketable securities	$	267,346	$	100	$	(25	)	$	267,421