Operating leases (Details) (USD $)	Dec. 31, 2012
Lease expensesincurred	$ 886,000
Primary lease Minimum payments 2013	942
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	$ 3,883