Stockholders' Equity

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY

Initial Public Offering

On April 4, 2012, the Company completed its initial public offering ("IPO"), issuing 10,315,151 shares of common stock at an offering price of $6.00 per share. The net proceeds from the sale of the shares were $53.8 million, after deducting the underwriters’ discounts and commissions of $3.3 million and other offering costs of $4.8 million. Upon consummation of the IPO, the Company’s 22,220,856 outstanding shares of convertible preferred stock ($93.6 million carrying value) were automatically converted into 25,171,017 shares of common stock, and the $21.2 million outstanding balance of principal and accrued paid-in-kind interest in convertible notes were automatically converted into 3,533,988 shares of common stock at a conversion price equal to the IPO price of $6.00 per share. As a result, the Company recorded a charge of $2.8 million to interest expense in 2012 for the extinguishment of debt related to the unamortized debt issuance costs and debt discounts.

Common Stock Warrants

Prior to its IPO, the Company issued convertible preferred stock warrants in connection with several financing transactions. These warrants automatically converted into warrants to purchase common stock upon the consummation of the IPO.

As of December 31, 2013, warrants to purchase 293,474 shares of the Company's common stock remained outstanding with exercise prices ranging from $5.27 to $6.17. Such warrants are exercisable and will expire on various dates from 2016 through 2021.