Preferred Stock Warrant Liability (Tables)

12 Months Ended

Dec. 31, 2015

Class Of Stock Disclosures [Abstract]

Summary of Assumptions and Inputs Used in Determining Fair Value of Preferred Stock Warrant Liability Valued Using Black-Scholes Option-Pricing Model

The following assumptions and inputs were used in determining the fair value of the preferred stock warrant liability valued using the Black-Scholes option-pricing model:

	Year Ended December 31,
	2015			2014			2013
Risk-free interest rate		2.40	%		2.17	%		3.20	%
Expected term (in years)		8.2			8.7			9.7
Expected volatility		91.2	%		84.0	%		86.0	%
Expected dividend yield		0	%		0	%		0	%
Fair value of Series A-2 convertible preferred stock	$	17.26		$	17.18		$	2.07

Summary of Rollforward of Fair Value of Preferred Stock Warrant Liability

The following table provides a rollforward of the fair value of the Company’s preferred stock warrant liability:

	Fair Value
Balance as of December 31, 2012	$	—
Issuance of Series A-2 preferred stock warrant		156
Loss on revaluation		8
Balance as of December 31, 2013		164
Loss on revaluation		1,418
Balance as of December 31, 2014	$	1,582
Loss on revaluation		7
Reclassification to stockholders’ equity		(1,589	)
Balance as of December 31, 2015	$	—