Convertible Promissory Notes, Related Parties (Details) - USD ($)				3 Months Ended	12 Months Ended
	Feb. 13, 2018	Nov. 20, 2015	Dec. 10, 2014	Mar. 31, 2018	Dec. 31, 2017
Convertible Promissory Notes, Related Parties (Details) [Line Items]
Proceeds from Convertible Debt				$ 25,000,000
Debt Instrument, Interest Rate, Stated Percentage				8.00%
Debt Instrument, Increase, Accrued Interest					$ 6,300,000
Debt Instrument, Unamortized Discount					$ 400,000
Debt Conversion, Converted Instrument, Shares Issued (in Shares)	1,571,702
Debt Instrument, Convertible, Conversion Price (in Dollars per share)	$ 9.05
Debt Conversion, Converted Instrument, Amount	$ 14,200,000			$ 250,000
Other Ownership Interests, Contributed Capital	21,400,000
Note Purchase Agreement [Member]
Convertible Promissory Notes, Related Parties (Details) [Line Items]
Proceeds from Convertible Debt			$ 18,400,000
Second Note Purchase Agreement [Member]
Convertible Promissory Notes, Related Parties (Details) [Line Items]
Proceeds from Convertible Debt		$ 11,000,000
Convertible Promissory Notes [Member]
Convertible Promissory Notes, Related Parties (Details) [Line Items]
Debt Instrument, Face Amount	35,600,000
Debt Instrument, Periodic Payment, Interest	6,600,000
Debt Instrument, Periodic Payment, Principal	$ 29,400,000
Notes Issued in 2014 [Member]
Convertible Promissory Notes, Related Parties (Details) [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Liability				1,900,000
Debt Issuance Costs, Net				20,000
Notes Issued in 2015 [Member]
Convertible Promissory Notes, Related Parties (Details) [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Liability				1,300,000
Debt Issuance Costs, Net				$ 7,000