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Related Party Transactions - Additional Information (Details) - USD ($)			1 Months Ended	12 Months Ended
	Jul. 01, 2016	Aug. 13, 2014	Sep. 30, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Orthotec LLC, litigation settlement
Related Party Transaction [Line Items]
Payments of settlement				$ 31,800,000		$ 17,500,000
Judgment assessed by court for (against) company		$ (49,000,000)
Orthotec LLC, litigation settlement \| Indemnification Agreement
Related Party Transaction [Line Items]
Indemnification obligation payments (less than $0.1 million)				100,000	$ 100,000
Orthotec LLC, litigation settlement \| HealthpointCapital, LLC
Related Party Transaction [Line Items]
Payments of settlement	$ 1,000,000			1,100,000
Judgment assessed by court for (against) company			$ (5,000,000)
HealthpointCapital, LLC
Related Party Transaction [Line Items]
Incurred expenses (less than $.1 million)				100,000	100,000
Payable liability (less than $.1 million)					$ 100,000
Outstanding receivable or payable balance				$ 0