Subsequent events (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended			1 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jul. 31, 2013 Subsequent Event [Member]	Jun. 30, 2013 Subsequent Event [Member]
Subsequent Event [Line Items]
Payments to Acquire Businesses, Gross					$ 50
Class of Warrant or Right, Exercise Price of Warrants or Rights	3.85		4	3.00
Warrants Exercised				50,000
Proceeds from Warrant Exercises	$ 3,047	$ 0		$ 150
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period				50,000