Basis of Presentation - Narrative (Details)			3 Months Ended
	Feb. 23, 2018 USD ($)	Jan. 01, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Nov. 17, 2017 USD ($)	Dec. 31, 2016 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Working Capital Deficiency			$ (600,000)
Deferred revenue, net			7,391,371		$ 11,760,327
Total Stockholders' Deficit			(14,445,743)		(21,224,797)
Net income (loss)			506,877	$ (1,112,197)
Net cash used in operating activities			1,212,349	133,620
Cash and cash equivalents			4,563,260	$ 3,431,763	$ 1,011,472		$ 3,391,528
Cash Period Decrease			3,600,000
Entity number of employees					81
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in deferred revenue			(13,139,819)		$ (18,360,690)
Increase in contract assets			3,400,000		$ 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 | 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			(5,016,354)
Net income (loss)			$ 114,171
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