Stockholders' Equity - Warrant Activity and Warrants Outstanding (Detail)	3 Months Ended
	Mar. 31, 2013
Class of Warrant or Right [Roll Forward]
Warrants outstanding, beginning balance	38,332,389
Common Stock Warrants Issued	1,545,000
Issued-additional number	1,154,659	[1]
Warrants outstanding, ending balance	41,032,048

[1] Associated with reset provisions contained within the October 27, 2006 warrant contracts.