Stockholders' Equity (Private Placements of Securities) (Details) (USD $)	1 Months Ended		12 Months Ended								1 Months Ended										1 Months Ended		1 Months Ended
	May 31, 2013	Apr. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007	Jun. 30, 2013	Nov. 30, 2005	Sep. 30, 2009 Norsk Hydro [Member] Private Placement [Member]	Oct. 31, 2008 Norsk Hydro [Member] Private Placement [Member]	Mar. 31, 2008 Norsk Hydro [Member] Private Placement [Member]	Aug. 31, 2007 Norsk Hydro [Member] Private Placement [Member]	Mar. 31, 2007 Norsk Hydro [Member] Private Placement [Member]	May 31, 2008 Norsk Hydro [Member] Private Placement [Member]	Dec. 13, 2007 Norsk Hydro [Member] Private Placement [Member]	Jun. 30, 2007 Norsk Hydro [Member] Private Placement [Member]	Dec. 31, 2013 TFG Radiant [Member]	Jan. 31, 2012 TFG Radiant [Member]	Aug. 31, 2011 TFG Radiant [Member] Private Placement [Member]	Aug. 12, 2011 TFG Radiant [Member] Private Placement [Member]	Mar. 31, 2008 Class B Warrant [Member] Private Placement [Member]	Aug. 31, 2007 Class B Warrant [Member] Private Placement [Member]
Equity Offering [Line Items]
Secondary public offering, shares (in shares)	2,500,000	2,500,000									769,230	2,421,801	2,341,897	934,462	1,600,000						6,400,000
Proceeds from issuance of private placement			$ 1,425,000	$ 11,000,039	$ 7,360,000	$ 4,999,995	$ 36,647,693	$ 15,962,257			$ 5,000,000	$ 15,000,000	$ 28,400,000	$ 10,480,000	$ 9,200,000						$ 7,360,000
Percent of common stock outstanding												35.00%		23.00%	23.00%	27.00%		35.00%	26.00%
Number of units issued																							1,689,905	1,965,690
Maximum related party allowable ownernship percentage																	35.00%
Share price (in dollars per share)											$ 6.50									$ 0.50	$ 1.15	$ 0.73
Option to acquire additional shares																					9,500,000
Option to acquire additional shares, exercise price (in dollars per share)																					$ 1.55
Transferred shares																				8,067,390
Transferred shares, value																				4,000,000
Proceeds from sale of common stock, per share									$ 0.57	$ 0.04
Proceeds from issuance of common stock	$ 1,400,000	$ 1,425,000