Capital Stock - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended	6 Months Ended				1 Months Ended	6 Months Ended			6 Months Ended					1 Months Ended	6 Months Ended
	Aug. 09, 2013	May 17, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Mar. 31, 2013	May 17, 2013 Common Stock [Member]	Jun. 30, 2014 Common Stock [Member]	Jun. 30, 2013 Common Stock [Member]	Jun. 30, 2014 Employee Stock Purchase Plan [Member]	Jun. 30, 2014 Warrant 1 [Member]	Jun. 30, 2014 Warrant 2 [Member]	Jun. 30, 2014 Warrant 3 [Member]	May 17, 2013 Warrant 3 [Member]	Jun. 29, 2012 Warrant 4 [Member]	Jun. 30, 2013 Placement Agent Warrants [Member]	Jun. 30, 2014 Placement Agent Warrants [Member]	Aug. 09, 2013 Placement Agent Warrants [Member]	May 17, 2013 Placement Agent Warrants [Member]
Stockholders Equity [Line Items]
Convertible preferred stock, par value			$ 0.001
Convertible preferred stock, shares authorized			6,000,000
Common stock, shares authorized		150,000,000	300,000,000		300,000,000	150,000,000
Common stock, par value			$ 0.001		$ 0.001
Common stock, outstanding or reserved for issuance			198,381,556
Common stock, shares outstanding			122,516,317		122,448,707
Shares reserved for potential exercise			6,148,700
Shares reserved for exercise of outstanding warrants											1,750,000	437,158	35,081,967		437,158
Expiration date of warrants											Mar. 05, 2015	Jun. 29, 2017
Proceeds from private placement of preferred stock			$ 0	$ 12,000,000			$ 12,000,000	$ 12,000,000
Convertible preferred stock current conversion price								$ 39,089,161
Shares Reserved For Exercise Of Rights										571,277
Class Of Warrant Or Right Exercisable Number Of Warrants Or Rights		32,786,885											20,655,737
Warrant Exercisable Expiration Date													May 17, 2020
Shares Reserved For Issuance Of Common Stock And Warrants			31,876,137
Additional Pro Rata Investment in Common Stock and Warrants			5,000,000					5,000,000
Convertible Preferred Stock, Shares Issued upon Conversion									39,089,161
Stock Issued During Period Shares New Issues				43,715,847			43,715,847
Percentage Of Warrants Exercisable			63.00%
Percentage Of Warrants Exercisable After Shareholder Approval			37.00%
Increase In Common Stock Shares Authorized		300,000,000
Increase In Interest Expense	11,000
Allocated Share-based Compensation Expense																	780,000
Warrants To Purchase Of Common Stock																	2,295,082
Warrants Fair Value Disclosure																5,358,708		5,369,676	5,072,129
Warrants exercise price per share		$ 0.2745					$ 0.2745				$ 1.30	$ 0.2745	$ 0.2745	$ 0.2745			$ 0.2745
Non cash Interest Expenses																$ 286,579