Cash and cash equivalents and restricted cash (Details Textual) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash and cash equivalents	$ 3,443	$ 3,704	$ 8,434
Cash, FDIC Insured Amount	3,165
Cash, Uninsured Amount	278
Letter Of Credit [Member]
Other Restricted Assets, Noncurrent	39
Convertible Preferred Series Stock Agreement [Member]
Other Restricted Assets, Noncurrent	$ 2,000