Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) (USD $)	0 Months Ended							1 Months Ended	12 Months Ended
	Apr. 30, 2014	Mar. 11, 2014	Jan. 15, 2014	Sep. 16, 2013	Feb. 20, 2013	Mar. 29, 2012	Mar. 28, 2012	Feb. 28, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Increase (Decrease) in Stockholders' Equity
Net proceeds from public offerings			$ 27,970,256	$ 10,600,000	$ 1,900,000	$ 2,085,525	$ 13,704,745	$ 2,300,000	$ 165,722,618		$ 12,873,452
Public offering, common stock, net (in shares)	22,600,000	3,902,440	10,000,000	18,600,000	18,910,000
Exercise of warrants (in shares)									23,832,038
Reduction in warrant liability									83,444,574
Common Stock
Increase (Decrease) in Stockholders' Equity
Increase in additional paid-in capital									18,441,730
Public offering, common stock, net (in shares)									36,502,440	[1]	43,101,800	[2]	14,950,000
Exercise of warrants (in shares)									23,918,429	[3]	22,494,987	[4]
Warrants
Increase (Decrease) in Stockholders' Equity
Proceeds from warrants issued								2,451,028	11,773,240
Increase in additional paid-in capital								5,878,146
Public offering, common stock, net (in shares)								22,494,987
Reduction in warrant liability								11,198,822
Warrants | Common Stock
Increase (Decrease) in Stockholders' Equity
Increase in additional paid-in capital								$ 11,198,822

[1] As a result of the January, March and April 2014 public offerings discussed in Note 5, Stockholders’ Equity, the Company received net proceeds of $165,722,618 of which $11,773,240 in value was ascribed to the warrants issued in the January 2014 public offering. The associated warrants have been separately valued and classified as a liability on the accompanying consolidated balance sheet.

[2] As a result of the 2013 public offerings discussed in Note 5, Stockholders’ Equity, the Company received net proceeds of $12,873,452, of which $2,451,028 in value was ascribed to the warrants issued in the February 2013 public offering.

[3] Pursuant to the exercise of warrants, additional paid-in capital was increased by $18,441,730 from the issuance of 23,832,038 shares of common stock. Additionally, paid-in capital was increased by $83,444,574 and warrant liability was reduced by $83,444,574 (the fair value of the warrants on the exercise date).

[4] Pursuant to the exercise of warrants, additional paid-in capital was increased by $5,878,146 from the issuance of 22,494,987 shares of common stock. Additionally, paid-in capital was increased by $11,198,822 and warrant liability was reduced by $11,198,822 (the fair value of the warrants on the exercise date).