Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Estimated Fair Value of Stock Option Award

The estimated fair value of each stock option award granted was determined on the date of grant using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for option grants during the six months ended June 30, 2014. No options were granted during the six months ended June 30, 2013.

	Three Months Ended June 30,			Six Months Ended June 30,
	2014	2013		2014	2013
Common Stock Options
Risk free interest rate	1.66%		—	1.66 - 1.77%		—
Expected option term	5.5 years		—	5.5 - 6.0 years		—
Expected volatility of common stock	71.06%		—	71.06 - 73.21%		—
Expected dividend yield	0.0%		—	0.0%		—

Summary of Estimated Fair Value of Employee Stock Purchase Plan Award

The estimated fair value of each employee stock purchase plan award was determined on the date of grant using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for options grants during the six months ended June 30, 2014. The employee stock purchase plan did not become active until March 2014.

	Three and Six Months Ended June 30,
	2014	2013
Employee Stock Purchase Plan
Risk free interest rate	0.08%		—
Expected option term	6.0 months		—
Expected volatility of common stock	73.21%		—
Expected dividend yield	0.0%		—

Summary of Non-Cash Share-Based Compensation Expense

The Company recognized non-cash stock-based compensation expense to employees and directors in its research and development and its general and administrative functions as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Research and development	$	104,759	$	1,563	$	197,424	$	4,064
General and administrative		160,451		1,563		291,096		2,188
Total stock-based compensation expense	$	265,210	$	3,126	$	488,520	$	6,252