Warrant Exercise (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended		118 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013
Class of Warrant or Right [Line Items]
Liability Reclassed to Equity		$ 412
Cash Received	101	210	13,180
Equity Warrants
Class of Warrant or Right [Line Items]
Number Of Warrants Exercised	49,315	115,073
Liability Warrants
Class of Warrant or Right [Line Items]
Number Of Warrants Exercised		373,617
Common Stock Issued
Class of Warrant or Right [Line Items]
Number Of Warrants Exercised	49,315	192,603
Cash exercises
Class of Warrant or Right [Line Items]
Cash Received	101	210
Cash exercises | Equity Warrants
Class of Warrant or Right [Line Items]
Number Of Warrants Exercised	49,315	102,744
Cash exercises | Common Stock Issued
Class of Warrant or Right [Line Items]
Number Of Warrants Exercised	49,315	102,744
Cashless Exercise
Class of Warrant or Right [Line Items]
Liability Reclassed to Equity		$ 412
Cashless Exercise | Equity Warrants
Class of Warrant or Right [Line Items]
Number Of Warrants Exercised		12,329
Cashless Exercise | Liability Warrants
Class of Warrant or Right [Line Items]
Number Of Warrants Exercised		373,617
Cashless Exercise | Common Stock Issued
Class of Warrant or Right [Line Items]
Number Of Warrants Exercised		89,859