Contingently Issuable Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		3 Months Ended		9 Months Ended
	Dec. 10, 2010	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value of Contingently Issuable Common Stock
Beginning balance				$ 9,300
Fair Value Adjustment of Contingent Payment for the nine months ended September 30, 2018		$ (5,000)	$ (800)	(4,300)	$ (3,400)
Ending balance		5,000		5,000
Nelix Milestones
Business Acquisition [Line Items]
Number of shares contingently issuable (in shares)	10.2
Estimated fair value of contingent payment	$ 28,200
PMA Milestone
Business Acquisition [Line Items]
Common shares value		$ 15,000		$ 15,000
Number of shares contingently issuable (in shares)				3.3
Share price (in dollars per share)		$ 4.5		$ 4.5
Closing stock price (in dollars per share)		$ 1.91		$ 1.91
Average daily closing stock price				30 days
Days prior to milestone achievement announcement				5 days
Contingent consideration, at fair value hypothetical value		$ 6,400		$ 6,400
Nellix
Business Acquisition [Line Items]
Purchase price common shares (in shares)	3.2
Common shares value	$ 19,400