Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

Financial Instruments Measured at Fair Value on 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):

	Fair Value Measurements at September 30, 2014
	(unaudited)
	Total		Level 1		Level 2		Level 3
Assets
Money market funds	$	175,083	$	175,083	$	—	$	—
	Fair Value Measurements at December 31, 2013
	Total		Level 1		Level 2		Level 3
Assets
Money market funds	$	12,761	$	12,761	$	—	$	—
Liabilities
Convertible preferred stock warrant liability	$	474	$	—	$	—	$	474
Convertible preferred stock call option liability		21		—		—		21
Total liabilities	$	495	$	—	$	—	$	495

Summary of Changes in Fair Value of Financial Instruments

The following table sets forth a summary of the changes in the fair value of the Company’s Level III financial instruments as follows (in thousands):

	Convertible			Convertible
	preferred stock			preferred stock
	call option			warrant
	liability			liability
Balance at January 1, 2014	$	21		$	474
Fair value of call option liability recognized upon issuance of preferred stock		—			—
Change in fair value recorded in other income (expense), net		9,560			2,279
Conversion of preferred stock into common stock and reclassification to permanent equity		(9,581	)		(2,753	)
Balance at September 30, 2014	$	—		$	—
	Convertible			Convertible
	preferred stock			preferred stock
	call option			warrant
	liability			liability
Balance at January 1, 2013	$	—		$	433
Issuance of financial instruments		990			—
Fair value of call option liability recognized upon issuance of preferred stock		(127	)		—
Change in fair value recorded in other income (expense), net		(863	)		(1	)
Balance at September 30, 2013	$	-		$	432