Nature of Business and Basis of Presentation - Additional Information (Detail) (USD $)	1 Months Ended														12 Months Ended		150 Months Ended
	Mar. 23, 2012	Mar. 28, 2012	May 10, 2010	Apr. 30, 2010	Mar. 08, 2010	Jan. 29, 2010	Dec. 08, 2009	Nov. 04, 2009	Sep. 30, 2009	Aug. 12, 2009	Jun. 30, 2009	May 13, 2009	Feb. 12, 2009	Feb. 25, 2008	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2010	Dec. 30, 2010	Jul. 02, 2008	Feb. 04, 2008	May 31, 2003	Dec. 31, 2002	Aug. 31, 2001
Basis of Presentation [Line Items]
Reverse stock split ratio	1.6667
Exercise price of warrant																			7.20	6.00	9.00	32.40	21.00	39.00
Net proceeds from issuance of stock and warrants		$ 10,403,000	$ 536,000	$ 297,000	$ 322,000	$ 308,000	$ 310,000	$ 296,000	$ 305,000	$ 287,000	$ 473,000	$ 801,000	$ 1,548,000	$ 3,381,000
Unrestricted cash and cash equivalents															9,364,000	6,397,000	9,364,000	5,891,000
Net losses applicable to common stockholders															(10,881,000)	(12,713,000)	(80,272,000)
Net total capital through sale and issuance of common stock and warrants														1,044,000	68,800,000
Net cash used in operating activities															(7,500,000)	(5,676,000)	(58,553,000)
Common Stock
Basis of Presentation [Line Items]
Issuance of common stock and warrants		2,666,722
Warrants to purchase shares of common stock		1,333,361
Warrant
Basis of Presentation [Line Items]
Exercise price of warrant		5.63
Common Stock and Warrants
Basis of Presentation [Line Items]
Gross proceeds from issuance of stock and warrants		12,000,000
Net proceeds from issuance of stock and warrants		$ 10,403,000
Reverse Split
Basis of Presentation [Line Items]
Reverse stock split ratio	1.6667