Orthotec Settlement - Additional Information (Details)				1 Months Ended			12 Months Ended
	Jul. 01, 2016 USD ($)	Oct. 01, 2014 USD ($)	Aug. 13, 2014 USD ($) installment	Sep. 30, 2014 USD ($)	Apr. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Settlement amount to be contributed							$ 5,000,000	$ 5,000,000
Litigation settlement, remaining outstanding balance including interest							0
Orthotec LLC, litigation settlement
Loss Contingencies [Line Items]
Judgment assessed by court for (against) company			$ 49,000,000
Payments of settlement					$ 15,750,000	$ 1,750,000	36,200,000
Number of quarterly installments | installment			28
Litigation settlement interest, quarterly installments, amount			$ 1,100,000
Litigation settlement, final installment amount			700,000
Litigation settlement, remaining outstanding balance including interest							21,600,000
Orthotec LLC, litigation settlement | HealthpointCapital, LLC
Loss Contingencies [Line Items]
Judgment assessed by court for (against) company				$ 5,000,000
Payments of settlement	$ 1,000,000						1,100,000
Settlement amount to be contributed							$ 5,000,000
Beginning fourth quarter of 2014 | Orthotec LLC, litigation settlement
Loss Contingencies [Line Items]
Settlement amount, remaining balance		$ 31,500,000
Litigation settlement interest, quarterly installments, amount			$ 1,100,000
Litigation settlement interest rate			7.00%
Litigation settlement payments, quarterly payment amount			$ 1,100,000
Final installment | Orthotec LLC, litigation settlement
Loss Contingencies [Line Items]
Number of quarterly installments | installment			1