2. Summary of significant accounting policies (Details) - Valuation for Accounts Receivable (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Valuation for Accounts Receivable [Abstract]
Balance, beginning of period	$ 66	$ 70	$ 57
Additions charged to costs and expenses			1
Acquisition of business			15
Deductions	(3)	(4)	(3)
Balance, end of period	$ 63	$ 66	$ 70