Collaboration and Commercial Technology Licensing Agreements (Epic) (Details)	1 Months Ended	24 Months Ended
	Jun. 30, 2016 USD ($) item	Dec. 31, 2017 USD ($)	Mar. 31, 2018 USD ($)
Collaboration agreements
Debt securities investment			$ 84,511,000
Exclusive distribution rights Epic's AR-V7 Nucleus Detect
Collaboration agreements
Amount invested in notes		$ 7,500,000
Debt securities investment		7,100,000
Deferred cost		$ 375,000
Obligation upon achievement of certain milestones	$ 4,000,000
Number of milestones needed to be achieved for conversion into preferred stock | item	1
Investment in preferred stock per collaboration agreement	$ 2,500,000
Term of agreement	10 years