Common Stock Warrant Liability (Tables)

12 Months Ended

Dec. 31, 2012

Common Stock Warrant Liability [Abstract]

Estimated fair value of warrants accounted for derivative liabilities

Selected terms and estimated fair value of warrants accounted for as derivative are as follows:

						Fair Value of Warrants (in thousands)
	Number of				Warrant	Value at		December 31
	Warrant Shares		Exercise		Expiration	Issuance
Issuance Date	Issuable		Price		Date	Date		2012		2011
5/13/2009		466,667	$	17.25	5/13/2014	$	3,360	$	–	$	82
2/23/2010		916,667		12.75	2/23/2015		5,701		104		554
2/22/2011		4,948,750		2.80	2/22/2016		8,004		6,201		6,360
								$	6,305	$	6,996