Net Income (Loss) Per Share - Potential Shares of Common Stock Excluded from Diluted Net ( loss ) Income Per Share (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Impairment Effects on Earnings Per Share [Line Items]
Options to purchase common shares	4,340,750	1,524,160	1,833,130
Outstanding warrants and options to purchase warrants	27,443,727	17,443,727	1,265,000
Potential shares of common stock excluded from diluted net (loss) income per share	65,061,481	27,321,407	10,546,125
Amended and Restated Convertible Note [Member]
Impairment Effects on Earnings Per Share [Line Items]
Amended and Restated notes	28,748,424	8,353,518	7,447,995
Amended and Restated Reimbursement Note [Member]
Impairment Effects on Earnings Per Share [Line Items]
Amended and Restated notes	1,274,334
Amended and Restated Bridge Notes [Member]
Impairment Effects on Earnings Per Share [Line Items]
Amended and Restated notes	3,254,246