Description of Business and Significant Accounting Policies - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended			0 Months Ended	12 Months Ended
	Dec. 31, 2012	Feb. 28, 2011	Dec. 31, 2013 Candidate	Dec. 31, 2011	Dec. 31, 2010	Feb. 18, 2014 Subsequent Event [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Maximum [Member]
Subsidiary, Sale of Stock [Line Items]
Number of VDA drug candidates tested			2
Reverse stock split of the Company's common stock	0.083	0.050
Accumulated deficit	$ 225,432,000		$ 238,508,000
Cash	4,946,000		7,005,000	9,972,000	4,602,000
Gross proceeds in a public offering of common stock and warrants						12,000,000
Restricted cash	$ 20,000		$ 0
Estimated useful lives of the assets							3 years	5 years
Term of license agreement			15 years 6 months
Period of inspection of product			30 days
Percentage payment on gross margin of distributor's sales			20.00%