Concentrations of credit risk (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Concentrations of credit risk Details
One customer gross revenue	10.00%
Two customers of gross revenue		10.00%
Company's gross revenues from Customer A	7.00%
Two vendor purchased of merchandise	10.00%
One vendor purchased of merchandise		10.00%