Cost of revenue

12 Months Ended

Dec. 31, 2016

Other Income And Expenses [Abstract]

Cost of revenue

21. Cost of revenue

Cost of revenue consists of the following:

	Year ended December 31,
	2014		2015		2016
Personnel expenses	$	943,105	$	1,013,209	$	1,061,501
Operational expenses		390,441		432,535		446,922
Depreciation and amortization		44,542		47,803		46,284
	$	1,378,088	$	1,493,547	$	1,554,707