Commitments and contingencies (Tables)

12 Months Ended

Dec. 31, 2014

Commitments and contingencies

Schedule of operating lease expense

	Year ended December 31,
	2014		2013		2012
Operating lease expense	$	1,549,343	$	1,509,465	$	1,515,189

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

Years ending December 31,
2015	$	1,583,575
2016		1,409,433
2017		125,671
2018		5,489
2019		—
Thereafter		—
Total minimum lease payments	$	3,124,168

Schedule of leased property under capital leases

	December 31,
	2014			2013
Computer hardware	$	1,989,836		$	1,607,602
Computer software		290,095			258,306
Total capital leases, gross		2,279,931			1,865,908
Less: Accumulated depreciation		(1,039,927	)		(662,082	)
Total capital leases, net	$	1,240,004		$	1,203,826

Schedule of future minimum rental payment under capital leases

Years ending December 31,
2015	$	499,187
2016		281,438
2017		91,840
2018		3,620
2019		—
Thereafter		—
Total minimum lease payments		876,085
Less: Amounts representing taxes, included in total minimum lease payments*		—
Net minimum lease payments		876,085
Less: Amounts representing interest payments		(59,367	)
Present value of net minimum lease payments	$	816,718

* Tax amounts related to capital lease payments are inconsequential.

Schedule of future minimum payments under those agreements

Years ending December 31,
2015	$	406,667
2016		366,667
2017		416,667
2018		300,000
2019		—
Thereafter		—
Total payments	$	1,490,001