Summary of significant accounting policies (Details)	12 Months Ended
	Dec. 31, 2018
Property [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment estimated useful life	20 years
Leasehold improvements [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment estimated useful life	5 years
Vehicles [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment estimated useful life	5 years
Office equipment and furniture [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property and equipment estimated useful life	3 years