Warrants - Additional Information (Detail) (USD $)	1 Months Ended				12 Months Ended								124 Months Ended				12 Months Ended								12 Months Ended					12 Months Ended				1 Months Ended				12 Months Ended				1 Months Ended	12 Months Ended		1 Months Ended
	Feb. 23, 2007 Y	May 03, 2006	Jun. 06, 2005	Dec. 22, 2004 Y	Dec. 31, 2013 Y	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009 Y	Dec. 31, 2006	Dec. 31, 2005 Y	Dec. 31, 2004 Y	Dec. 31, 2013 Y	Dec. 31, 2008	Jan. 31, 2004	Sep. 30, 2003	Dec. 31, 2013 Equity	Dec. 31, 2012 Equity	Dec. 31, 2011 Equity	Dec. 31, 2010 Equity	Dec. 31, 2012 Liability Reclassed To Equity	Dec. 31, 2013 Liability Reclassed To Equity	Dec. 31, 2011 Liability Reclassed To Equity	Dec. 31, 2010 Liability Reclassed To Equity	Dec. 31, 2009 J. P. Morgan Securities LLC	Dec. 31, 2013 Placement warrants for services performed, expiration date September 15, 2014	Dec. 31, 2013 Liability	Dec. 31, 2012 Liability	Dec. 31, 2011 Liability	Dec. 31, 2013 Liability Warrants	Dec. 31, 2012 Liability Warrants	Dec. 31, 2011 Liability Warrants	Dec. 31, 2011 Exercise of Warrants	Oct. 31, 2009 Private Placement	Feb. 23, 2007 Private Placement	May 03, 2006 Private Placement Y	May 31, 2005 Private Placement	Dec. 31, 2009 Private Placement Y	Dec. 31, 2013 Private Placement Y	Dec. 31, 2006 Private Placement	Jun. 06, 2005 Private Placement	Sep. 15, 2009 Private Placement Placement Agents	Dec. 31, 2009 Private Placement Placement Agents	Dec. 31, 2009 Registered direct offering	Feb. 23, 2007 Investor	May 03, 2006 Investor Y
Class of Warrant or Right [Line Items]
Warrant issued					184,367																																419,786
Warrant exercised					135,346	553,914	2,516,968	95,505			12,500																							136,986			11,083
Warrant outstanding					10,539,767								10,539,767				135,346	186,297	2,351,417	70,738	373,617	0	165,551	24,767		8,235,076											408,703
Value of warrant issued																																					$ 1,600,000
Sale of stock price per share																																					$ 4.75	$ 1.825		$ 4.63	$ 4.31
Revised price for warrants																																					$ 4.69	$ 4.25						$ 3.93
Issuable price for common stock																																												$ 3.10
Warrants liabilities					11,776,000	12,962,000							11,776,000	72,000
Warrants to purchase an aggregate of shares of common stock		799,126		62,621	799,126				8,206,520		50,000	62,621																							177,302	799,126		2,910,954				138,617	138,617		1,182,015	2,397,392
Warrants issued																									464,520
Warrant exercise price	$ 5.75			$ 4.75	$ 5.09																				$ 4.02										$ 5.75			$ 2.04				$ 2.04
Warrant exercisable Period			7 years																						6 months													5 years
Warrant term	5 years								5 years
Estimated fair value of warrant					3,500,000				22,900,000				3,500,000																						709,000	3,500,000		4,207,000							4,700,000	9,600,000
Expected volatility	93.00%	100.00%		134.00%	134.00%				105.00%		109.00%	134.00%	134.00%																									105.00%	100.00%
Risk free interest	4.71%	5.01%		3.93%	3.93%				2.14%		4.39%	3.93%	3.93%																									2.41%
Expected life	5			7	7				5		5	7	7																							7		5	7							5
Expected dividend yield	0.00%	0.00%		0.00%	0.00%				0.00%		0.00%	0.00%	0.00%																									0.00%	0.00%
Common stock price per share in public offering					$ 3.50								$ 3.50		$ 0.50	$ 0.50
Classified warrants														18,866,000													11,800,000	13,000,000	19,400,000
Other income (expense)					(579,000)	(13,000)	39,000						4,122,000																	(1,200,000)	(6,100,000)	(7,600,000)	(300,000)
General administrative expenses				$ 251,000	$ 15,661,000	$ 19,523,000	$ 14,984,000				$ 45,000	$ 251,000	$ 103,979,000
Warrants cancelled										37,500
Conversion of Warrants to Common Stock					112,808	259,660	2,377,571	39,225
Warrants expired																	706,708	1,359,317	277,910	12,500	579