13. Income taxes (Details) - Unrecognized Tax Benefit Rollforward (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Unrecognized Tax Benefit Rollforward [Abstract]
Unrecognized tax benefits as of January 1	$ 251,000	$ 228,000
Tax positions taken during the current period	79,000	23,000
Lapse of statute of limitations	(224,000)
Unrecognized tax benefits as of December 31	$ 106,000	$ 251,000