Share-Based Payments (Tables)

12 Months Ended

Dec. 31, 2015

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Stock Option Activity and Related Information

A summary of the Company’s stock option activity and related information follows:

	Shares		Weighted-Average Exercise Price		Remaining Contractual Life (in years)
Outstanding at December 31, 2014	1,438,528		$	4.93	7.86
Granted	802,828		8.66
Exercised	(78,585	)	0.74
Cancelled or forfeited	(359,197	)	7.40
Outstanding at December 31, 2015	1,803,574		$	6.28	7.78
Exercisable at December 31, 2015	855,711		$	4.80	7.11
Vested and expected to vest at December 31, 2015 (1)	1,589,145		$	6.58	7.88

(1)Represents the number of vested options, plus the number of unvested options expected to vest.

Summary of Status and Changes of Unvested Restricted Stock

A summary of the status of unvested restricted stock as of December 31, 2015 and 2014, and changes during the year ended December 31, 2015 are presented below:

	Restricted Stock		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2014	125,027		$	5.39
Granted	6,660		4.03
Vested	(90,030	)	2.67
Unvested at December 31, 2015	41,657		$	11.05

Summary of Restricted Stock Unit Activity

A summary of the status of restricted stock units is presented below:

	Restricted Stock Units		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2014	—		$	—
Granted	221,400		2.82
Vested	(70,468	)	2.76
Unvested at December 31, 2015	150,932		$	2.85

Non-employee Stock Options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Estimation of Fair Value of Stock Option Granted using Black-Scholes Option-Pricing Model Assumptions

The fair value of each non-employee stock option granted is estimated using the Black-Scholes option-pricing model based on assumptions noted in the following table:

	Year Ended December 31,
	2015	2014	2013
Risk-free interest rate	1.19-2.26%	1.67-2.04%	1.82-2.99%
Expected dividend yield	0.00%	0.00%	0.00%
Expected option life (years)	10	10	10
Expected stock price volatility	67.24-92.40%	57.65-80.98%	76.28-78.14%

Employees And Directors Stock Options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Estimation of Fair Value of Stock Option Granted using Black-Scholes Option-Pricing Model Assumptions

The fair value of each stock option granted to employees and directors was estimated on the date of grant using the Black-Scholes option-pricing model based on the assumptions noted in the following table:

	Year Ended December 31,
	2015	2014	2013
Risk-free interest rate	1.42-1.92%	1.67-2.02%	1.09-2.07%
Expected dividend yield	—%	—%	—%
Expected term (in years)	5.75-6	5.75-6	6
Expected volatility	69.06-74.11%	60.00-69.58%	72.13-77.80%