Stockholders' Equity (Changes in stockholders' equity) (Details) (USD $)	3 Months Ended		9 Months Ended			12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2012			$ 15,030,303
Net Loss	(15,895,372)	(10,325,464)	(33,792,515)		(23,388,120)	(31,900,000)	(27,500,000)	(47,000,000)
Other comprehensive loss	25,268	110,625	(56,828)		106,585
Stock based compensation			1,561,422
Public offering common stock, net			10,422,424	[1]
Exercise of warrants			9,051,810	[2]
Stock dividend
Balance at September 30, 2013	2,216,616		2,216,616			15,030,303
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2012			384,048
Balance at December 31, 2012 (in shares)			38,404,764
Net Loss
Stock based compensation			19,690
Stock based compensation (in shares)			1,968,986
Public offering common stock, net			431,018	[1]
Public offering common stock, net (in shares)			43,101,800	[1]
Exercise of warrants			189,964	[2]
Exercise of warrants (in shares)			18,996,400	[2]
Stock dividend			1,320
Stock dividend (in shares)			132,017
Balance at September 30, 2013	1,026,040		1,026,040
Balance at September 30, 2013 (in shares)	102,603,967		102,603,967
Additional Paid-in-Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2012			801,840,491
Net Loss
Stock based compensation			1,541,732
Public offering common stock, net			9,991,406	[1]
Exercise of warrants			8,861,846	[2]
Stock dividend			67,891
Balance at September 30, 2013	822,303,366		822,303,366
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2012			1,004,412
Net Loss
Other comprehensive loss			(56,828)
Stock based compensation
Public offering common stock, net
Exercise of warrants
Stock dividend
Balance at September 30, 2013	947,584		947,584
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2012			(1,552,382)
Balance at December 31, 2012 (in shares)			165,906
Net Loss
Stock based compensation
Public offering common stock, net
Exercise of warrants
Stock dividend
Balance at September 30, 2013	(1,552,382)		(1,552,382)
Balance at September 30, 2013 (in shares)	165,906		165,906
Accumulated Deficit [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2012			(786,646,266)
Net Loss			(33,792,515)
Stock based compensation
Public offering common stock, net
Exercise of warrants
Stock dividend			(69,211)
Balance at September 30, 2013	$ (820,507,992)		$ (820,507,992)

[1] As a result of the 2013 public offering discussed further below, 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. The associated warrants have been separately valued and classified as a liability on the accompanying consolidated balance sheet. After consideration of the fair value ascribed to the warrants and the net proceeds of the overall offering, it was determined that the fair value of the warrants and the common stock exceeded the net proceeds received as part of the offering and consequently additional paid-in capital was reduced by $354,586.

[2] Pursuant to the exercise of warrants, additional paid-in capital was increased by $2,659,496 from the issuance of 18,996,400 shares of common stock. Additionally, paid-in capital was increased by $6,202,350 and warrant liability was reduced by $6,202,350 (the fair value of the warrants on the exercise date).