Intangible assets (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Belize Water Production and Supply Agreement [Member]	Dec. 31, 2003 Desal Co [Member]
Equity Method Investment, Ownership Percentage	43.50%	43.50%			100.00%
Finite Lived Intangible Asset Amortization Period				23 years
Payment for NSC option agreement	$ 300,000	$ 0	$ 0