Subsequent Events	6 Months Ended
Jun. 30, 2013
Subsequent Events
Subsequent Events	11. Subsequent Events On July 17, 2013, the Company sold an aggregate of 5,750,000 shares of its common stock at a price to the public of $5.00 per share and issued $125.0 million aggregate principal amount of 4.50% convertible senior notes due 2020 in concurrent underwritten public offerings. As a result of the concurrent Common Stock Offering and Convertible Notes Offering, the Company received net proceeds of approximately $147.4 million, including the net proceeds from the exercise in full by the underwriters in the Common Stock Offering of an option to purchase additional shares of common stock and after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. The Company issued the 4.50% convertible senior notes due 2020 under an indenture dated as of July 17, 2013 between the Company and Wells Fargo Bank, National Association, as trustee (the “Trustee”), as supplemented by the supplemental indenture dated as of July 17, 2013 between the Company and the Trustee. As a result of the completion of the concurrent Common Stock Offering and Convertible Notes Offering and the Company receiving aggregate gross proceeds of at least $75 million in one or more transactions prior to December 1, 2013, the Company may elect to extend the interest-only period under the Loan Agreement with Hercules by six months so that the aggregate outstanding principal balance of the loans issued pursuant to the Loan Agreement would be repaid in monthly installments starting on June 1, 2014 and continuing through November 1, 2016. On July 10, 2013, in connection with the Convertible Notes Offering, the Company and Hercules entered into an amendment, consent and waiver to the Loan Agreement that permitted the Convertible Notes Offering and the issuance of the 4.50% convertible senior notes due 2020.

11. Subsequent Events

On July 17, 2013, the Company sold an aggregate of 5,750,000 shares of its common stock at a price to the public of $5.00 per share and issued $125.0 million aggregate principal amount of 4.50% convertible senior notes due 2020 in concurrent underwritten public offerings. As a result of the concurrent Common Stock Offering and Convertible Notes Offering, the Company received net proceeds of approximately $147.4 million, including the net proceeds from the exercise in full by the underwriters in the Common Stock Offering of an option to purchase additional shares of common stock and after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company.

The Company issued the 4.50% convertible senior notes due 2020 under an indenture dated as of July 17, 2013 between the Company and Wells Fargo Bank, National Association, as trustee (the “Trustee”), as supplemented by the supplemental indenture dated as of July 17, 2013 between the Company and the Trustee.

As a result of the completion of the concurrent Common Stock Offering and Convertible Notes Offering and the Company receiving aggregate gross proceeds of at least $75 million in one or more transactions prior to December 1, 2013, the Company may elect to extend the interest-only period under the Loan Agreement with Hercules by six months so that the aggregate outstanding principal balance of the loans issued pursuant to the Loan Agreement would be repaid in monthly installments starting on June 1, 2014 and continuing through November 1, 2016.

On July 10, 2013, in connection with the Convertible Notes Offering, the Company and Hercules entered into an amendment, consent and waiver to the Loan Agreement that permitted the Convertible Notes Offering and the issuance of the 4.50% convertible senior notes due 2020.