Basis of Presentation - Narrative (Details)			3 Months Ended		9 Months Ended
	Feb. 23, 2018 USD ($)	Jan. 01, 2018 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Nov. 17, 2017 USD ($)	Dec. 31, 2016 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Working Capital Deficiency			$ (3,000,000)		$ (3,000,000)
Deferred revenue, net			6,859,592		6,859,592		$ 11,760,327
Total Stockholders' Deficit			(12,027,338)		(12,027,338)		(21,224,797)
Net income (loss)			(332,429)	$ 1,429,173	(829,656)	$ (322,825)
Net cash used in operating activities			(300,000)		(331,722)	(1,551,421)
Cash and cash equivalents			2,827,296	$ 1,751,310	2,827,296	$ 1,751,310	$ 1,011,472		$ 3,391,528
Cash Period Decrease			1,800,000
Entity number of employees							81
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in deferred revenue			(9,572,434)		(9,572,434)		$ (18,360,690)
Increase in contract assets			2,100,000		2,100,000		$ 0
Finance Commitment Loan | HCP-FVA, LLC
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Aggregate amount of debt	$ 3,000,000							$ 3,000,000
Loan And Security Agreement, Short-Term Loan [Member] | HCP-FVA, LLC
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Aggregate amount of debt	500,000							$ 500,000
Loan And Security Agreement, Long-Term Loan | HCP-FVA, LLC
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Aggregate amount of debt	$ 2,500,000.0
Prime rate | Secured Debt | Investor | Finance Commitment Loan
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Variable interest rate	0.75%
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in accumulated deficit		$ 8,900,000
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Deferred revenue, net			(3,622,199)		(3,622,199)
Net income (loss)			$ (591,429)		$ (1,745,930)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in deferred revenue		5,400,000
Increase in contract assets		3,100,000
Increase in prepaid expenses and other current assets		$ 400,000