Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Summary of Fair Value Assets and Liabilities Measured 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 December 31, 2016
	Total		Level 1		Level 2		Level 3
Assets
Money market funds	$	136,481	$	136,481	$	—	$	—
U.S. government agency obligations	$	12,075	$	—	$	12,075	$	—
Corporate securities	$	3,999	$	—	$	3,999	$	—
	$	152,555	$	136,481	$	16,074	$	—

	Fair Value Measurements atDecember 31, 2015
	Total		Level 1		Level 2		Level 3
Assets
Money market funds	$	111,533	$	111,533	$	—	$	—

Summary of Fair Value Measurement of Available-for-sale Securities

The following table is a summary of amortized cost, unrealized gain and loss, and fair value (in thousands) of the Company’s marketable securities by contractual maturities:

	FairValue Measurements at December 31, 2016
	Amortized Cost		Unrealized Gain		Unrealized Loss		Fair Value
Cash equivalents (due within 90 days)	$	136,481	$	—	$	—	$	136,481
Short-term investments (due within one year)		4,072		—		—		4,072
Long-term investments (due between one and two years)		11,988		14		—		12,002
	$	152,541	$	14	$	—	$	152,555

Summary of Changes in Fair Value of Company's Level 3 Financial Instruments

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

	Convertible preferred stock call option liability, net
Balance at December 31, 2014		314
Change in fair value recorded in statement of operations and    comprehensive income (loss)		(314	)
Balance at December 31, 2015	$	—
Change in fair value recorded in statement of operations and    comprehensive income (loss)	$	—
Balance at December 31, 2016	$	—