Earnings Per Share (Summary of potential dilutive common shares) (Details)	9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of dilutive potential common shares	42,755,013		11,695,791
Stock options outstanding [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of dilutive potential common shares	4,145,689		1,999,521
Unvested restricted stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of dilutive potential common shares			275,262
Common stock warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of dilutive potential common shares	27,636,465	[1]	9,421,008	[1]
Preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of dilutive potential common shares	10,972,859	[2]

[1] On May 31, 2011, the Company issued 7,128,563 warrants as part of an underwritten public offering. As a result of the March 28 and 29, 2012 and February 20 and 21, 2013 public offerings, the May 8, 2013 issuance of Series C redeemable convertible preferred stock, and the September 16, 2013 public offering described in Note 5, the number of warrants increased to 22,995,365. Additionally, on February 20, 2013 the Company issued 23,637,500 warrants as part of an underwritten public offering. Of the warrants issued in February 2013, 18,996,400 were exercised as of September 30, 2013.

[2] The preferred stock amount represents the dilutive potential common shares of the 10,431 shares of Series C redeemable convertible preferred stock issued on May 16, 2013.