Stock-based compensation expense (Tables)

9 Months Ended

Sep. 30, 2017

Stock incentive plan

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

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
Processing and service costs	$	16,760	$	35,051	$	86,340	$	134,112
Selling, general and administrative expenses		176,595		282,408		681,534		1,364,246
Total stock-based compensation expense	$	193,355	$	317,459	$	767,874	$	1,498,358

Summary of stock-based compensation expense recognized by type

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
Stock options	$	120,772	$	217,537	$	503,995	$	766,766
Restricted stock awards		72,583		99,922		263,879		731,592
Total stock-based compensation expense	$	193,355	$	317,459	$	767,874	$	1,498,358