Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Share Based Fair Value Assumptions

The fair value of options granted were estimated using the Black-Scholes-Merton option pricing model based on the assumptions in the table below:

	Years ended December 31,
	2015	2014	2013
Expected dividend yield	0%	0%	0%
Expected volatility	45%-56%	46%-63%	62%-63%
Risk-free interest rate	1.44% - 1.95%	1.60% - 2.30%	1.64% - 1.98%
Expected life (in years)	5.5 – 6.3	5.2 – 7.0	5.7 – 6.1

Schedule of Stock Option Activity

The following table summarizes the Company’s stock option activity, including grants to non-employees, for the year ended December 31, 2015:

	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)
Options outstanding at December 31, 2014		5,423,741		$	2.82		7.79
Granted		4,407,758			2.76
Forfeited		(434,025	)		4.70
Cancelled		(467,985	)		6.80
Exercised		(628,670	)		0.41
Options outstanding at December 31, 2015		8,300,819			2.63		8.23

Schedule of Stock Options Outstanding

The following table summarizes information about stock options outstanding at December 31, 2015:

	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)
Exercisable at December 31, 2015		3,096,827	$	2.12		6.58
Vested or expected to vest at December 31, 2015		7,953,823	$	2.61		8.18