Summary of Information with Regard to Outstanding Warrants Issued in Connection with Equity and Debt Financings and Consultants (Parenthetical) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012
February 25, 2008 Common Stock Transaction
Equity [Line Items]
Warrant issuance date	Feb. 25, 2008
February 12, 2009 Series B-1 Transaction
Equity [Line Items]
Warrant issuance date	Feb. 12, 2009
May 13, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	May 13, 2009
June 30, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	Jun. 30, 2009
April 15, 2009 Consultant Warrants
Equity [Line Items]
Warrant issuance date	Apr. 15, 2009
May 1, 2009 Consultant Warrants
Equity [Line Items]
Warrant issuance date	May 01, 2009
June 30, 2009 Consultant Warrants
Equity [Line Items]
Warrant issuance date	Jun. 30, 2009
July 26, 2009 Consultant Warrants
Equity [Line Items]
Warrant issuance date	Jul. 26, 2009
August 12, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	Aug. 12, 2009
September 30, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	Sep. 30, 2009
November 4, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	Nov. 04, 2009
December 8, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	Dec. 08, 2009
January 29, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	Jan. 29, 2010
March 8, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	Mar. 08, 2010
April 30, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	Apr. 30, 2010
May 10, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issuance date	May 10, 2010
June 15, 2010 Consultant Warrants
Equity [Line Items]
Warrant issuance date	Jun. 15, 2010
December 9, 2010 Consultant Warrants
Equity [Line Items]
Warrant issuance date	Dec. 09, 2010
December 30, 2010 Placement Agent Warrants
Equity [Line Items]
Warrant issuance date	Dec. 30, 2010
Warrant 4 | February 25, 2008 Common Stock Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.70
Warrant 5 | February 12, 2009 Series B-1 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | May 13, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | June 30, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | August 12, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | September 30, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | November 4, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | December 8, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | January 29, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | March 8, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | April 30, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 5 | May 10, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.5
Warrant 6 | February 12, 2009 Series B-1 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | May 13, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | June 30, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | August 12, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | September 30, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | November 4, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | December 8, 2009 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | January 29, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | March 8, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | April 30, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.50
Warrant 6 | May 10, 2010 Series B-2 Transaction
Equity [Line Items]
Warrant issued price per share	$ 0.5
First Issuance | May Twenty Five Twenty Ten Consultant Warrants
Equity [Line Items]
Warrant issuance date	May 25, 2010
Second Issuance | May Twenty Five Twenty Ten Consultant Warrants
Equity [Line Items]
Warrant issuance date	May 25, 2010