Fair Value Measurements and Investments - Schedule of Valuation Methodology and Unobservable Inputs for Level 3 Assets and Liabilities Measured at Fair Value (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)
Spinal Kinetics [Member] | Revenue Discount Rate
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Consideration transferred	$ 20,700
Spinal Kinetics [Member] | Revenue Discount Rate | Minimum [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Business combination contingent consideration liability measurement input	7.41
Spinal Kinetics [Member] | Revenue Discount Rate | Maximum [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Business combination contingent consideration liability measurement input	7.49
Spinal Kinetics [Member] | Payment Discount Rate | Minimum [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Business combination contingent consideration liability measurement input	4.33
Spinal Kinetics [Member] | Payment Discount Rate | Maximum [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Business combination contingent consideration liability measurement input	4.40
Spinal Kinetics [Member] | Projected Year of Payment | Minimum [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Business combination contingent consideration liability measurement period	2021
Spinal Kinetics [Member] | Projected Year of Payment | Maximum [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Business combination contingent consideration liability measurement period	2022
Spinal Kinetics [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Spinal Kinetics contingent consideration estimated fair value at January 1	$ 35,400	$ 42,700
Increase (decrease) in fair value recognized in acquisition-related amortization and remeasurement	300	(6,900)
Payment made	(15,000)
Spinal Kinetics contingent consideration estimated fair value at June 30	20,700	$ 35,800
Neo Medical [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Neo Medical Convertible Loan	$ 6,500
Fair value implied volatility	21.90%
Fair value discount rate	86.00%