Income taxes (Details 3) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Operating loss carryforwards - Mexico	$ 4,923,026	$ 4,462,746
Land basis difference	702,547	414,101
Start-up costs	747,215	668,161
Operating loss carryforwards - United States	0	150,758
Valuation allowances	(6,372,788)	(5,695,766)
Deferred Tax Assets, Net of Valuation Allowance	0	0
Deferred tax liabilities:
Property and equipment	205,827	129,041
Intangible assets	819,066	1,786,200
Deferred Tax Liabilities, Gross	1,024,893	1,915,241
Net deferred tax liability	$ 1,024,893	$ 1,915,241