11. Commitments and contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Rent Expense	$ 1,005,000	$ 1,030,000	$ 918,000
Operating Leases, Future Minimum Payments Due, Next Twelve Months	832,000
Operating Leases, Future Minimum Payments, Due in Two Years	821,000
Operating Leases, Future Minimum Payments, Due in Three Years	563,000
Operating Leases, Future Minimum Payments, Due in Five Years	$ 78,000