Fair value (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets measured at fair value
Cash and Cash Equivalents	$ 4,160	$ 10,014
Restricted Cash	250	375
Short term investments	4,469	6,191
Total Assets measured at fair value	8,879	16,580
Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Cash and Cash Equivalents	4,160	10,014
Restricted Cash	250	375
Short term investments
Total Assets measured at fair value	4,410	10,389
Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value
Cash and Cash Equivalents
Restricted Cash
Short term investments	4,469	6,191
Total Assets measured at fair value	4,469	6,191
Fair Value, Inputs, Level 3 [Member]
Assets measured at fair value
Cash and Cash Equivalents
Restricted Cash
Short term investments
Total Assets measured at fair value