Segment information - Information about revenue, profit and assets (Details)	3 Months Ended			9 Months Ended
	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) item	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment information
Number of reportable segments | item				2
Cost of sales included in processing and services costs	$ 2,878,088		$ 3,776,232	$ 9,902,879	$ 10,399,830
Long-lived assets	6,800,000			$ 6,800,000		$ 7,400,000
Number of geographical regions in which the entity conducts its business | item				3
Net Revenue:
Net revenue	13,621,239		12,618,413	$ 40,409,128	37,434,542
Gross Profit:
Total gross profit	7,961,862		6,150,091	22,299,047	19,163,533
Income from operations before provision for income taxes:
Total gross profit	7,961,862		6,150,091	22,299,047	19,163,533
Selling, general and administrative expenses	5,222,560		5,657,740	15,908,166	14,840,844
Restructuring charges	229,121	$ 125,000	283,726	354,389	283,726
Income from operations	2,510,181		208,625	6,036,492	4,038,963
Interest expense	(88,669)		(10,372)	(186,366)	(38,815)
Interest income	428		392	1,250	1,183
Other income	93,016			93,016
Total other income (expense), net	4,775		(9,980)	(92,100)	(37,632)
Income from operations before provision for income taxes	2,514,956		198,645	5,944,392	4,001,331
Operating segments
Gross Profit:
Total gross profit	10,306,583		8,893,532	30,305,001	27,230,806
Income from operations before provision for income taxes:
Total gross profit	10,306,583		8,893,532	30,305,001	27,230,806
Corporate allocated cost of sales
Gross Profit:
Total gross profit	2,344,721		2,743,441	8,005,954	8,067,273
Income from operations before provision for income taxes:
Total gross profit	2,344,721		2,743,441	8,005,954	8,067,273
Multi-currency processing services
Segment information
Cost of sales included in processing and services costs	500,000		1,000,000	1,900,000	2,300,000
Net Revenue:
Net revenue	8,175,476		7,792,329	24,768,314	23,535,783
Multi-currency processing services | Operating segments
Gross Profit:
Total gross profit	7,642,109		6,759,538	22,871,389	21,203,228
Income from operations before provision for income taxes:
Total gross profit	7,642,109		6,759,538	22,871,389	21,203,228
Payment processing services
Net Revenue:
Net revenue	5,445,763		4,826,084	15,640,814	13,898,759
Payment processing services | Operating segments
Gross Profit:
Total gross profit	2,664,474		2,133,994	7,433,612	6,027,578
Income from operations before provision for income taxes:
Total gross profit	2,664,474		2,133,994	7,433,612	6,027,578
APAC
Net Revenue:
Net revenue	3,962,539		3,573,478	11,541,521	11,836,523
APAC | Multi-currency processing services | Operating segments
Gross Profit:
Total gross profit	3,942,457		3,547,202	11,467,607	11,741,027
Income from operations before provision for income taxes:
Total gross profit	3,942,457		3,547,202	11,467,607	11,741,027
Americas
Net Revenue:
Net revenue	2,634,887		1,870,722	7,264,448	5,114,772
Americas | Multi-currency processing services | Operating segments
Gross Profit:
Total gross profit	2,470,294		1,761,686	6,766,889	4,799,928
Income from operations before provision for income taxes:
Total gross profit	2,470,294		1,761,686	6,766,889	4,799,928
EMEA
Net Revenue:
Net revenue	1,578,050		2,348,129	5,962,345	6,584,488
EMEA | Multi-currency processing services | Operating segments
Gross Profit:
Total gross profit	1,229,358		1,450,650	4,636,893	4,662,273
Income from operations before provision for income taxes:
Total gross profit	$ 1,229,358		$ 1,450,650	$ 4,636,893	$ 4,662,273