Other Long-Term Liabilities - Deferred (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Funds received from investor	$ 2.8
Deferred payment arrangements value	$ 3.2	$ 3.6
Minimum
Leasehold improvements and long-term liability amortization period	5 years
Maximum
Leasehold improvements and long-term liability amortization period	10 years