Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of Fair Value Financial Assets and Liabilities Measured on Recurring Basis

The following table sets forth the fair value of the Company’s financial assets and liabilities measured on a recurring basis by level within the fair value hierarchy:

	December 31, 2016
	Level 1		Level 2		Level 3		Total
	(in thousands)
Financial Assets
Money market funds	$	107,043	$	—	$	—	$	107,043
Restricted money market funds		200		—		—		200
Total financial assets	$	107,243	$	—	$	—	$	107,243

	December 31, 2015
	Level 1		Level 2		Level 3		Total
	(in thousands)
Financial Assets
Money market funds	$	148,604	$	—	$	—	$	148,604
Restricted money market funds		225		—		—		225
Total financial assets	$	148,829	$	—	$	—	$	148,829

Summary of the Changes in the Estimated Fair Value of the Company's Preferred Stock Warrant Liabilities

The following table provides a summary of the changes in the estimated fair value of the Company’s preferred stock warrant liabilities, which were measured at fair value on a recurring basis using unobservable inputs (Level 3) until their exercise in 2015 (in thousands):

	December 31, 2015
	(in thousands)
Fair value, beginning balance	$	1,810
Fair value of preferred stock warrants exercised		(19,253	)
Change in fair value of preferred stock warrants		17,443
Fair value, ending balance	$	—