Commitments and contingencies (Tables)

12 Months Ended

Dec. 31, 2015

Commitments and contingencies

Schedule of operating lease expense

	Year ended December 31,
	2015		2014		2013
Operating lease expense	$	1,577,764	$	1,549,343	$	1,509,465

Schedule of future minimum rental payments under non-cancelable operating leases

Years ending December 31,
2016	$	1,519,039
2017		126,827
2018		4,477
2019		—
2020		—
Thereafter		—
Total minimum lease payments	$	1,650,343

Schedule of leased property under capital leases

	December 31,
	2015		2014
Computer hardware	$	2,145,668	$	1,989,836
Computer software		319,683		290,095
Total capital leases, gross		2,465,351		2,279,931
Less: Accumulated depreciation		(1,415,472)		(1,039,927)
Total capital leases, net	$	1,049,879	$	1,240,004

Schedule of future minimum rental payment under capital leases

Years ending December 31,
2016	$	311,472
2017		160,563
2018		43,210
2019		—
2020		—
Thereafter		—
Total minimum lease payments		515,245
Less: Amounts representing taxes, included in total minimum lease payments(*)		—
Net minimum lease payments		515,245
Less: Amounts representing interest payments		(28,134)
Present value of net minimum lease payments	$	487,111

(*)Tax amounts related to capital lease payments are inconsequential.

Schedule of future minimum payments under those agreements

Years ending December 31,
2016	$	366,667
2017		416,667
2018		300,000
2019		—
2020		—
Thereafter		—
Total payments	$	1,083,334