Sales of Common Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended		6 Months Ended
	Oct. 31, 2012	Jul. 31, 2008	Jun. 30, 2013
Units issued in direct offering		6,686,650	4,600,000
Equity issuance, price per share		$ 2.68
Proceeds from direct offering		$ 17,500	$ 10,000
Common stock authorized for issuance under prior shelf registration statement with SEC, dollar amount	$ 50,000
Minimum [Member]
Equity issuance, price per share			$ 2.06
Maximum [Member]
Equity issuance, price per share			$ 2.63