Segment information - Information about revenue, profit and assets (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Segment information
Number of reportable segments | item	2
Cost of sales included in processing and services costs	$ 14,860,804	$ 13,483,282	$ 13,048,294
Long-lived assets	$ 7,400,000	9,100,000
Number of geographical regions in which the entity conducts its business | item	3
Net Revenue:
Net revenue	$ 52,815,088	47,368,739	46,566,065
Gross Profit:
Total gross profit	27,050,624	23,481,778	22,281,509
Income from operations before provision for income taxes:
Total gross profit	27,050,624	23,481,778	22,281,509
Selling, general and administrative expenses	20,408,308	18,370,691	22,241,656
Restructuring charges	283,726	1,227,204
Income from operations	6,358,590	3,883,883	39,853
Interest expense	(57,575)	(65,122)	(66,905)
Interest income	1,579	2,212	1,038
Other income	89,494	139,875	88,889
Total other income, net	33,498	76,965	23,022
Income from operations before benefit (provision) for income taxes	6,392,088	3,960,848	62,875
Operating segments
Net Revenue:
Net revenue	38,189,095	34,919,585	33,650,276
Corporate allocated cost of sales
Net Revenue:
Net revenue	11,138,471	11,437,807	11,368,767
Multi-currency processing services
Segment information
Cost of sales included in processing and services costs	3,700,000	2,000,000	1,700,000
Net Revenue:
Net revenue	33,463,439	30,954,085	29,813,449
Gross Profit:
Total gross profit	29,741,106	28,908,610	28,133,922
Income from operations before provision for income taxes:
Total gross profit	29,741,106	28,908,610	28,133,922
Payment processing services
Net Revenue:
Net revenue	19,351,649	16,414,654	16,752,616
Gross Profit:
Total gross profit	8,447,989	6,010,975	5,516,354
Income from operations before provision for income taxes:
Total gross profit	8,447,989	6,010,975	5,516,354
APAC | Multi-currency processing services
Net Revenue:
Net revenue	16,265,076	16,621,147	15,666,192
Gross Profit:
Total gross profit	16,136,562	16,513,492	15,572,813
Income from operations before provision for income taxes:
Total gross profit	16,136,562	16,513,492	15,572,813
Americas | Multi-currency processing services
Net Revenue:
Net revenue	7,162,346	6,893,337	6,165,431
Gross Profit:
Total gross profit	6,725,223	6,733,037	6,045,441
Income from operations before provision for income taxes:
Total gross profit	6,725,223	6,733,037	6,045,441
EMEA | Multi-currency processing services
Net Revenue:
Net revenue	10,036,017	7,439,601	7,981,826
Gross Profit:
Total gross profit	6,879,321	5,662,081	6,515,668
Income from operations before provision for income taxes:
Total gross profit	$ 6,879,321	$ 5,662,081	$ 6,515,668