Warrant Liability (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Jul. 31, 2008	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Warrant Liability [Abstract]
Issuance of common stock, shares	6,686,650
Proceeds from direct offering	$ 17,500
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	$ 2,474