Long and short-term capital leases (Tables)

12 Months Ended

Dec. 31, 2015

Long and short-term capital leases

Schedule of long and short-term capital leases

	December 31,
	2015		2014
Capital leases to various lessors secured by financed equipment with interest rates ranging from 4.67% to 13.45%. Principal and interest are payable monthly through September 2018	$	487,111	$	816,718
Total long and short-term portions of capital leases		487,111		816,718
Less: short-term portion capital leases		(290,911)		(458,812)
Long-term portion of capital leases	$	196,200	$	357,906

Schedule of interest expense related to capital leases

	Year ended December 31,
	2015		2014		2013
Capital leases	$	46,958	$	61,591	$	60,106