Stock repurchases (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	0 Months Ended	12 Months Ended	0 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Apr. 02, 2013 Maximum
Equity, Class of Treasury Stock
Amount of common stock approved by the entity for a stock repurchase program			$ 10,000
Number of shares repurchased and retired under the stock repurchase program		722
Value of shares repurchased and retired under the stock repurchase program excluding commissions paid		4,820
Average price under the stock repurchase program (in dollars per share)		$ 6.68
Remaining amount authorized for the share repurchase program	$ 5,180