Changes in Warrant Liabilities (Detail) (USD $)	0 Months Ended	3 Months Ended	12 Months Ended	162 Months Ended
	May 21, 2008	Jun. 30, 2008	Dec. 31, 2011	Dec. 31, 2013
Warranty Liability [Line Items]
Beginning Balance			$ 861,000
Change in fair value of warrant liabilities	100,000	356,000	524,000	(9,022,000)
Intrinsic value of liability warrants exercised			$ (1,385)