Operating leases (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating leases Future Minimum Payments
Lease expensesincurred	$ 942,000	$ 924,000	$ 906,000
Primary lease Minimum payments 2014	961
Primary lease Minimum payments 2015	980
Primary lease Minimum payments 2016	1,000
Primary lease Minimum payments 2017	83
Primary lease Minimum payments total	$ 3,024