Warrants - Additional Information (Detail) (USD $)	1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended	109 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended		1 Months Ended	2 Months Ended	9 Months Ended		2 Months Ended
	May 31, 2012	Feb. 23, 2007	May 31, 2005	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2009	Sep. 30, 2012	Sep. 30, 2012 Liability Warrants [Member]	Sep. 30, 2011 Liability Warrants [Member]	Sep. 30, 2012 Liability Warrants [Member]	Sep. 30, 2011 Liability Warrants [Member]	Dec. 31, 2009 J. P. Morgan Securities LLC [Member]	Jan. 20, 2012 J. P. Morgan Securities LLC [Member]	May 31, 2005 Private Placement [Member]	Dec. 31, 2009 Private Placement [Member]	Sep. 30, 2012 Private Placement [Member]	Dec. 31, 2006 Private Placement [Member]	Dec. 31, 2009 Registered Direct Offering [Member]
Class of Warrant or Right [Line Items]
Warrant issued		1,359,317	579													419,786
Warrant exercised																		373,617
Warrant expired	579
Value of warrant issued																$ 1,600,000
sale of stock Price per share															$ 4.888	$ 4.75	$ 1.825		$ 4.63
Revised price for warrants																$ 4.69	$ 4.25			$ 3.93
Common stock warrants exercise price																	$ 2.04
Issuable price for common stock																				$ 3.10
Warrants to purchase an aggregate of shares of common stock								8,206,520
Warrants issued														464,520
Warrant exercise Price														$ 4.02
Warrant exercisable Period														6 months
Warrant term								5 years
Fair value of warrant								22,900,000
Expected volatility								105.00%
Risk free interest								2.14%
Expected life								5
Expected dividend yield								0.00%
Other income (expense)				$ (42,000)	$ 19,000	$ (65,000)	$ 26,000		$ 4,649,000	$ 3,900,000	$ 13,400,000	$ 2,500,000	$ 4,400,000
Warrants expiration date		Feb. 23, 2012	May 31, 2012
Warrant exercise price		$ 5.75	$ 3.93