Accrued expenses (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Bonus	$ 68,757	$ 611,228
Deferred revenue	823,137	881,715
Deferred incentive	462,809	1,087,591
Other	2,740,798	2,773,201
Total accrued expenses	$ 4,095,501	5,353,735
Recognition period of deferred revenue	12 months
Third party referral commissions	$ 1,000,000	$ 600,000
Maximum percentage of total current liabilities	10.00%	10.00%
Other long-term liabilities
Non-current portion of deferred revenue	$ 400,000	$ 700,000
Non-current portion of deferred incentive		$ 100,000