Stock-based compensation expense (Tables)

6 Months Ended

Jun. 30, 2017

Stock incentive plan

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

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2017		2016		2017		2016
Processing and service costs	$	27,145	$	50,255	$	69,580	$	99,061
Selling, general and administrative expenses		221,502		526,676		504,939		1,081,838
Total stock-based compensation expense	$	248,647	$	576,931	$	574,519	$	1,180,899

Summary of stock-based compensation expense recognized by type

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2017		2016		2017		2016
Stock options	$	155,717	$	267,833	$	383,223	$	549,229
Restricted stock awards		92,930		309,098		191,296		631,670
Total stock-based compensation expense	$	248,647	$	576,931	$	574,519	$	1,180,899