Basis of Presentation - Impact on the Balance Sheet from Adopting Revenue Recognition Standard (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets	$ 1,535,848	$ 1,244,494
Contract assets, net	1,178,851	0
Contract assets, net	939,930	0
Deferred revenue, net	6,859,592	11,760,327
Deferred tax liabilities, net	85,559	85,559
Deferred revenue, net	2,712,842	6,600,363
Accumulated deficit	(122,829,307)	$ (130,930,284)
Under Previous Guidance
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets	1,130,598
Contract assets, net	0
Contract assets, net	0
Deferred revenue, net	10,481,791
Deferred tax liabilities, net	85,559
Deferred revenue, net	3,751,315
Accumulated deficit	(130,014,010)
Accounting Standards Update 2014-09 | New Revenue Standard Adjustment
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Prepaid expenses and other current assets	405,250
Contract assets, net	1,178,851
Contract assets, net	939,930
Deferred revenue, net	(3,622,199)
Deferred tax liabilities, net	0
Deferred revenue, net	(1,038,473)
Accumulated deficit	$ 7,184,703