Goodwill and intangible assets - Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill
Goodwill, gross, at the Beginning of the period	$ 319,671	$ 362,063
Impact of change in Euro exchange rate	(32,819)	(42,392)
Goodwill, net, at the end of the period	$ 286,852	$ 319,671