Warrants - Additional Information (Detail) (USD $)	1 Months Ended				12 Months Ended							112 Months Ended		12 Months Ended									12 Months Ended					1 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, 2012 Y	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009 Y	Dec. 31, 2006	Dec. 31, 2005 Y	Dec. 31, 2004 Y	Dec. 31, 2012 Y	Dec. 31, 2008	Dec. 31, 2012 Equity	Dec. 31, 2011 Equity	Dec. 31, 2010 Equity	Dec. 31, 2012 Liability Reclassed To Equity	Dec. 31, 2011 Liability Reclassed To Equity	Dec. 31, 2010 Liability Reclassed To Equity	Dec. 31, 2012 Liabilities	Dec. 31, 2011 Liabilities	Dec. 31, 2010 Liabilities	Dec. 31, 2012 Liability Warrants	Dec. 31, 2011 Liability Warrants	Dec. 31, 2010 Liability Warrants	Dec. 31, 2011 Exercise of Warrants	Dec. 31, 2009 J. P. Morgan Securities LLC	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, 2012 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	May 31, 2005 Private Placement Remaining Amount	Dec. 31, 2009 Registered direct offering	Feb. 23, 2007 Investor	May 03, 2006 Investor Y
Class of Warrant or Right [Line Items]
Warrant issued																															419,786							408,703
Warrant exercised					553,914	2,516,968	95,505			12,500																		136,986			11,083
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													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%
Classified warrants													18,866,000							13,000,000	19,400,000	27,300,000
Other income (expense)					(13,000)	39,000	765,000					4,701,000											(6,100,000)	(7,600,000)	8,900,000	(300,000)
General administrative expenses				251,000	19,523,000	14,984,000	11,636,000			45,000	251,000	88,318,000
Warrants cancelled									37,500
Conversion of Warrants to Common Stock					$ 259,660	$ 2,377,571	$ 39,225
Classified warrants					11,197,454							11,197,454		186,297	2,351,417	70,738	373,617	165,551	24,767
Warrants expired														1,359,317	277,910	12,500	579