Warrant Liability (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2008	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Warrant Liability [Abstract]
Units issued in direct offering	6,686,650			4,600,000
Common shares per unit	1
Proceeds from direct offering	$ 17,500			$ 10,000
Shares entitled per warrant	0.5
Equity issuance, price per share	$ 2.68
Aggregate shares common stock callable by warrants	3,343,325
Exercise price of warrants	3.62
Change in fair value of warrant liability		267	(101)	267
Warrant liability						$ 267