Capital Stock - Additional Information (Detail) (USD $)	6 Months Ended						1 Months Ended	6 Months Ended			6 Months Ended						1 Months Ended	6 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 24, 2013	May 17, 2013	Dec. 31, 2012	Jun. 29, 2012	May 17, 2013 Common Stock [Member]	Jun. 30, 2013 Common Stock [Member]	Jun. 30, 2012 Common Stock [Member]	Jun. 30, 2013 Employee Stock Purchase Plan [Member]	Jun. 30, 2013 Warrant 2 [Member]	Jun. 30, 2013 Warrant 3 [Member]	Jun. 30, 2013 Warrant 4 [Member]	Jun. 30, 2013 Series A-1 Preferred Stock [Member]	Mar. 31, 2013 Series A-1 Preferred Stock [Member]	Jun. 29, 2012 Series A-1 Preferred Stock [Member]	Jun. 29, 2012 Series B Preferred Stock [Member]	Jun. 30, 2013 Series B Preferred Stock [Member]	Mar. 31, 2013 Series B Preferred Stock [Member]	Jun. 30, 2013 Placement Agent Warrants [Member]	May 17, 2013 Placement Agent Warrants [Member]
Stockholders Equity [Line Items]
Convertible preferred stock, par value	$ 0.001				$ 0.001
Convertible preferred stock, shares authorized	6,000,000				6,000,000
Convertible preferred stock, shares issued	0				5,500,000									5,000,000		5,000,000	500,000
Common stock, shares authorized	150,000,000			150,000,000	150,000,000
Common stock, par value	$ 0.001				$ 0.001
Common stock, outstanding or reserved for issuance	149,960,265
Common stock, shares outstanding	122,140,718				36,761,864
Shares reserved for conversion of Preferred to common stock														28,160,200
Shares reserved for potential exercise	4,277,280
Shares reserved for exercise of outstanding warrants						437,158					1,750,000	437,158	20,655,733
Warrants exercise price per share				0.2745		0.2745					1.30	0.2745	0.2745							0.2745
Expiration date of warrants	May 17, 2020										Mar. 05, 2015	Jun. 29, 2017	May 17, 2020
Proceeds from private placement of preferred stock	$ 12,000,000	$ 0					$ 12,000,000	$ 12,000,000									$ 3,000,000
Convertible preferred stock current conversion price														$ 0.3196				$ 0.2745
Net Proceeds from issuance of Series B Convertible preferred Stock																	2,700,000
Fair Value Adjustment of Warrants		104,907
Convertible preferred stock, liquidation preference				24,000,000	24,000,000										18,000,000				6,000,000
Convertible preferred stock, effective purchase price														$ 1.80				$ 6.00
Shares Reserved For Exercise Of Rights										699,376
Conversion of Stock, Shares Converted																		10,928,961
Stock Issued During Period, Shares, New Issues							43,715,847	43,715,847	0
Share Price							$ 0.2745
Proceeds from Issuance of Private Placement	12,000,000	0					12,000,000	12,000,000									3,000,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				32,786,885
Class Of Warrant Or Right Exercisable Percenage Immediately				63.00%
Class Of Warrant Or Right Exercisable Percenage Subject To Shareholder Approval				37.00%
Conversion of Stock, Shares Issued	39,089,161
Common Stock Shares Authorized Increase Proposal			300,000,000	300,000,000
Additional Pro Rata Investment In Common Stock And Warrants	5,000,000
Warrants Fair Value Disclosure																				5,358,708	5,072,129
Warrants To Purchase Of Common Stock																				2,295,082
Noncash interest expense																				286,579
Cash compansation expenses																				$ 780,000