Fair Value Measurements and Investments - Schedule of Valuation Methodology and Unobservable Inputs for Level 3 Assets and Liabilities Measured at Fair Value (Detail) - Spinal Kinetics [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Revenue Discount Rate
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Contingent consideration	$ 35,100
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
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
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
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
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
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