Potential Common Stock Equivalents Excluded from Calculation of Diluted Net Loss per Share (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the calculation of diluted net loss per share	43,153,175	46,099,541
Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the calculation of diluted net loss per share	5,884,050	2,302,000
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the calculation of diluted net loss per share	37,269,125	2,187,158
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the calculation of diluted net loss per share	0	39,089,161
Convertible Debt [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the calculation of diluted net loss per share	0	2,521,222