Warrant Exercise (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended		106 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012
Class of Warrant or Right [Line Items]
Liability Reclassed to Equity	$ 412	$ 265
Cash Received	210	12,293	12,959
Cash exercises
Class of Warrant or Right [Line Items]
Cash Received	210	12,293
Cashless exercises
Class of Warrant or Right [Line Items]
Liability Reclassed to Equity	$ 412	$ 265
Equity Warrants
Class of Warrant or Right [Line Items]
Warrant exercised	115,073	2,299,602
Equity Warrants | Cash exercises
Class of Warrant or Right [Line Items]
Warrant exercised	102,744	2,259,770
Equity Warrants | Cashless exercises
Class of Warrant or Right [Line Items]
Warrant exercised	12,329	39,832
Liability Warrants
Class of Warrant or Right [Line Items]
Warrant exercised	373,617	144,905
Liability Warrants | Cashless exercises
Class of Warrant or Right [Line Items]
Warrant exercised	373,617	144,905
Common Stock Issued
Class of Warrant or Right [Line Items]
Warrant exercised	192,603	2,319,078
Common Stock Issued | Cash exercises
Class of Warrant or Right [Line Items]
Warrant exercised	102,744	2,259,770
Common Stock Issued | Cashless exercises
Class of Warrant or Right [Line Items]
Warrant exercised	89,859	59,308