Summary of Warrants Outstanding (Detail)	12 Months Ended
	Dec. 31, 2012
Class of Warrant or Right [Line Items]
Number of Warrants	11,197,454
Placement warrants for services performed, expiration date May 3, 2013
Class of Warrant or Right [Line Items]
Number of Warrants	706,708
Exercise Price	5.09
Expiration Date	May 03, 2013
Investor warrants, expiration date September 15, 2014
Class of Warrant or Right [Line Items]
Number of Warrants	2,399,739
Exercise Price	2.04
Expiration Date	Sep. 15, 2014
Placement warrants for services performed, expiration date September 15, 2014
Class of Warrant or Right [Line Items]
Number of Warrants	40,298
Exercise Price	2.04
Expiration Date	Sep. 15, 2014
Investor warrants, expiration date December 9, 2014
Class of Warrant or Right [Line Items]
Number of Warrants	7,726,000
Exercise Price	4.02
Expiration Date	Dec. 09, 2014
Underwriter warrants for services performed, expiration date December 9, 2014
Class of Warrant or Right [Line Items]
Number of Warrants	324,709
Exercise Price	4.02
Expiration Date	Dec. 09, 2014