Stock-based compensation expense (Tables)

6 Months Ended

Jun. 30, 2016

Stock-based compensation expense and assumptions

Summary of stock-based compensation expense recognized by income statement classification

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Processing and service costs	$	50,255	$	50,084	$	99,061	$	100,581
Selling, general and administrative expenses		526,676		178,044		1,081,838		361,009
Total stock-based compensation expense	$	576,931	$	228,128	$	1,180,899	$	461,590

Summary of stock-based compensation expense recognized by type

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Stock options	$	267,833	$	124,433	$	549,229	$	255,705
Restricted stock awards		309,098		103,695		631,670		205,885
Total stock-based compensation expense	$	576,931	$	228,128	$	1,180,899	$	461,590