Summary of Significant Accounting Policies - Additional Information (Detail)	1 Months Ended		6 Months Ended	12 Months Ended
	Apr. 30, 2015 $ / shares shares	Dec. 31, 2011 $ / shares shares	Jun. 30, 2015 USD ($) Segment $ / shares	Dec. 31, 2012 shares	Dec. 31, 2014 USD ($)
Class of Warrant or Right [Line Items]
Number of segments | Segment			1
Maturity period for market accounts, money market funds and investments			90 days
Exercise price of warrants | $ / shares	$ 0.85
Common stock per unit | $ / shares			$ 1
Warrants issued per unit | $ / shares			$ 1
Number of shares issued upon Series B warrants exercise	35,715,000
Value of patent | $			$ 0
Accumulated other comprehensive income | $			49,800		$ 65,390
Outstanding Warrants [Member]
Class of Warrant or Right [Line Items]
Fair value of warrant liability | $			$ 1,044,000
December 2011 Financing [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by warrants		8,000,000
Term of warrant		5 years
Number of warrants issued upon Series B warrants exercise				2,700,000
December 2011 Financing [Member] | Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by warrants		8,000,000
Exercise price of warrants | $ / shares		$ 1.25
Term of warrant		90 days
Number of warrants exercised				2,700,000
Number of warrants expired				5,300,000
December 2011 Financing [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Number of shares issued upon Series B warrants exercise				2,700,000
December 2011 Financing [Member] | Common Stock [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Exercise price of warrants | $ / shares		$ 1.40
April 2015 Financing [Member] | Common Stock [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Exercise price of warrants | $ / shares	$ 0.6999999