Stockholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended				0 Months Ended	1 Months Ended			0 Months Ended				3 Months Ended					0 Months Ended	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013		Oct. 29, 2013	Feb. 05, 2014 Common Stock Equivalents of Convertible Preferred Stock [Member]	Feb. 28, 2014 Common Stock Equivalents of Convertible Preferred Stock [Member]	Mar. 31, 2014 Securities Purchase Agreement [Member]	Feb. 12, 2013 Shelf Registration Statement [Member]	Apr. 03, 2014 Subsequent Event [Member]	Mar. 07, 2014 Series B Prefunded Warrants [Member]	Mar. 05, 2014 Series B Prefunded Warrants [Member]	Mar. 31, 2013 Series B Prefunded Warrants [Member]	Mar. 31, 2014 Minimum [Member]	Mar. 31, 2013 Minimum [Member] ATM Program [Member]	Mar. 31, 2014 Maximum [Member]	Mar. 31, 2013 Maximum [Member] ATM Program [Member]	Oct. 29, 2013 Series B Prefunded Warrants [Member]	Oct. 29, 2013 Series A Warrants [Member]	Mar. 31, 2014 Series A Warrants [Member]
Securities Financing Transaction [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000	[1]
Preferred stock, par value	$ 0.10	$ 0.10	[1]
Preferred stock, shares issued	12,300	0	[1]		12,300	12,300
Preferred stock, par value					$ 0.10
Preferred stock stated value, per share					$ 1,000
Preferred stock converted to common stock, shares					14,642,857	14,642,857
Preferred stock converted to common stock, conversion price					$ 0.84	$ 0.84
Warrants issued to purchase common stock					13,297,297	13,297,297
Proceeds from issuance of warrants					$ 11,400,000	$ 11,400,000
Warrants issued to purchase common stock, exercise price					0.74	0.74												0.85
Warrants issued, exercisable term					5 years	5 years
Derivative fair value inception date	Feb. 05, 2014
Liquidated damages paid	(3,389,940)
Registration rights agreement description	Under the terms of the Registration Rights Agreement, the Company filed a registration statement on March 18, 2014, which was declared effective by the SEC on April 3, 2014. Should this registration statement cease to remain effective for more than ten consecutive calendar days or more than an aggregate of 15 calendar days during any 12-month period, the Company would be subject to additional liquidated damages of up to approximately $500,000
Additional liquidated damages payable									500,000
Common stock, shares authorized	95,000,000	95,000,000	[1]
Common stock, par value	$ 0.001	$ 0.001	[1]
Common stock issued	52,107,465	47,501,596	[1]	4,228,181
Warrants issued to purchase common stock																	4,343,247	6,857,142
Proceeds from issuance of common stock and warrants																		6,000,000
Warrants exercisable date																			May 01, 2014
Warrants expiry date																			May 01, 2019
Offering closed date							Oct. 31, 2013
Warrants exercised										2,343,247	2,000,000	0
Change in fair value of warrant liability	137,000
Public offering of common stock shares under underwriting agreement								6,100,000
Initial public offering price per share								$ 1.30
Gross proceeds from sale of common stock								7,900,000
Net proceeds from sale of common stock								7,300,000
Sales agreement termination date																Feb. 15, 2013
Number of common stock issued through company ATM program														4,700,000		6,600,000
Gross proceeds from sale of common stock														8,800,000		14,400,000
Net proceeds from sale of common stock														$ 8,500,000		$ 13,800,000
Number of outstanding common stock shares increased													47,501,596		52,107,465

[1] Derived from the audited balance sheet as of December 31, 2013