Significant Accounting Policies - Schedule of Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Notes and interest payable to related parties	$ 18,504,000		$ 18,504,000
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss per share	60,602,653	60,602,653	60,602,653	60,602,653
Outstanding Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss per share	3,189,660	1,209,200	3,189,660	1,209,200
Stock Purchase Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss per share	6,388,431	2,297,529	6,388,431	2,297,529
Unvested Restricted Common Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss per share	317,900		317,900