Summary of Significant Accounting Policies - Impact on the Balance Sheet from Adopting Revenue Recognition Standard (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accumulated deficit	$ (122,907,794)	$ (130,930,284)
Deferred Revenue, Noncurrent	2,506,898	6,600,363
Deferred tax liabilities, net	297,890	85,559
Deferred revenue, net	6,859,592	11,760,327
Contract assets, net	516,643	0
Prepaid expenses and other current assets	1,909,846	1,244,494
Contract assets, net	637,179	$ 0
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accumulated deficit	(128,362,754)
Deferred Revenue, Noncurrent	4,510,331
Deferred tax liabilities, net	297,890
Deferred revenue, net	8,735,622
Contract assets, net	0
Prepaid expenses and other current assets	1,488,171
Contract assets, net	0
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accumulated deficit	5,454,960
Deferred Revenue, Noncurrent	(2,003,433)
Deferred tax liabilities, net	0
Deferred revenue, net	(1,876,030)
Contract assets, net	516,643
Prepaid expenses and other current assets	421,675
Contract assets, net	$ 637,179