Contingently Issuable Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		3 Months Ended
	Dec. 10, 2010	Mar. 31, 2018	Mar. 31, 2017
Fair Value of Contingently Issuable Common Stock
Beginning balance		$ 9,300
Fair Value Adjustment of Contingent Payment for the three months ended March 31, 2018		(1,100)	$ 1,200
Ending balance		8,200
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
Number of shares contingently issuable (in shares)		3.3
Share price (in dollars per share)		$ 4.5
Closing stock price (in dollars per share)		$ 4.23
Average daily closing stock price		30 days
Days prior to milestone achievement announcement		5 days
Contingent consideration, at fair value hypothetical value		$ 14,100
Nellix
Business Acquisition [Line Items]
Purchase price common shares (in shares)	3.2
Common shares value	$ 19,400