Schedule of Shares Issued Upon Exercise of Warrants (Detail) - $ / shares	1 Months Ended							9 Months Ended
	Sep. 30, 2016	Apr. 30, 2016	Dec. 31, 2015	May 31, 2015	Feb. 28, 2015	Aug. 31, 2014	Dec. 31, 2013	Sep. 30, 2016
Derivative [Line Items]
Additional purchase of common stock shares								80,733,587
Shares Issued upon Warrant Exercises	(51,151,026)							(51,151,026)
Shares Underlying Warrants Outstanding	29,301,495							29,301,495
Series A
Derivative [Line Items]
Warrant, Issuance Date								Feb. 03, 2015
Warrants, Expiration date								Feb. 03, 2020
Warrant , Exercise Price	$ 0.30							$ 0.30
Additional purchase of common stock shares					2,216,667			2,216,667
Shares Issued upon Warrant Exercises	(1,988,335)							(1,988,335)
Shares Underlying Warrants Outstanding	228,332							228,332
Series B
Derivative [Line Items]
Warrant, Issuance Date								Feb. 03, 2015
Warrants, Expiration date								Aug. 03, 2015
Additional purchase of common stock shares					2,216,667			2,216,667
Shares Issued upon Warrant Exercises	(1,935,601)							(1,935,601)
Series C
Derivative [Line Items]
Warrant, Issuance Date								May 19, 2015
Warrants, Expiration date								May 19, 2020
Warrant , Exercise Price	$ 1.42							$ 1.42
Additional purchase of common stock shares				430,000				430,000
Shares Underlying Warrants Outstanding	430,000							430,000
Series D
Derivative [Line Items]
Warrant, Issuance Date								Dec. 11, 2015
Warrants, Expiration date								Dec. 11, 2020
Warrant , Exercise Price	$ 0.10							$ 0.10
Additional purchase of common stock shares			10,050,000					10,050,000
Shares Issued upon Warrant Exercises	(10,031,400)							(10,031,400)
Shares Underlying Warrants Outstanding	18,600							18,600
Series E
Derivative [Line Items]
Warrant, Issuance Date								Dec. 11, 2015
Warrants, Expiration date								Dec. 11, 2016
Additional purchase of common stock shares			8,000,000					8,000,000
Shares Issued upon Warrant Exercises	(8,000,000)							(8,000,000)
Series F
Derivative [Line Items]
Warrant, Issuance Date								Apr. 01, 2016
Warrants, Expiration date								Apr. 01, 2021
Warrant , Exercise Price	$ 0.30							$ 0.30
Additional purchase of common stock shares		10,292,858						10,292,858
Shares Underlying Warrants Outstanding	10,292,858							10,292,858
Series J
Derivative [Line Items]
Warrant, Issuance Date								Sep. 13, 2016
Warrants, Expiration date								Sep. 13, 2017
Warrant , Exercise Price	$ 0.01							$ 0.01
Additional purchase of common stock shares	3,700,000							3,700,000
Shares Issued upon Warrant Exercises	(3,700,000)							(3,700,000)
Series G
Derivative [Line Items]
Warrant, Issuance Date								Apr. 01, 2016
Warrants, Expiration date								Apr. 01, 2017
Additional purchase of common stock shares		6,571,429						6,571,429
Shares Issued upon Warrant Exercises	(6,571,429)							(6,571,429)
Series H
Derivative [Line Items]
Warrant, Issuance Date								Apr. 01, 2016
Warrants, Expiration date								Oct. 01, 2016
Warrant , Exercise Price	$ 0.75							$ 0.75
Additional purchase of common stock shares		20,585,716						20,585,716
Shares Issued upon Warrant Exercises	(18,008,716)							(18,008,716)
Shares Underlying Warrants Outstanding	2,577,000							2,577,000
Series I
Derivative [Line Items]
Warrant, Issuance Date								Sep. 13, 2016
Warrants, Expiration date								Sep. 13, 2021
Warrant , Exercise Price	$ 0.55							$ 0.55
Additional purchase of common stock shares	14,250,000							14,250,000
Shares Underlying Warrants Outstanding	14,250,000							14,250,000
2013 Warrants
Derivative [Line Items]
Warrant, Issuance Date								Dec. 16, 2013
Warrants, Expiration date								Dec. 16, 2018
Warrant , Exercise Price	$ 2.56							$ 2.56
Additional purchase of common stock shares							1,420,250	1,420,250
Shares Issued upon Warrant Exercises	(304,774)							(304,774)
Shares Underlying Warrants Outstanding	1,115,476							1,115,476
2014 Warrants
Derivative [Line Items]
Warrant, Issuance Date								Aug. 05, 2014
Warrants, Expiration date								Aug. 05, 2019
Warrant , Exercise Price	$ 1.86							$ 1.86
Additional purchase of common stock shares						1,000,000		1,000,000
Shares Issued upon Warrant Exercises	(610,771)							(610,771)
Shares Underlying Warrants Outstanding	389,229							389,229