Acquisitions - Additional Information (Detail) - USD ($)				12 Months Ended
	Feb. 06, 2019	Jan. 31, 2019	Apr. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill				$ 71,177,000	$ 72,401,000
Assigned Useful Life				9 years
Consideration for the assets acquired		$ 6,400,000
Developed Technology [Member]
Business Acquisition [Line Items]
Business acquisition, transfer from indefinite lived intangible assets to finite lived intangible assets	$ 26,800,000
Assigned Useful Life	10 years			10 years
Spinal Kinetics [Member]
Business Acquisition [Line Items]
Business acquisition date			Apr. 30, 2018
Business acquisition conversion of shares into net cash subject to adjustments			$ 45,000,000.0
Fair value of the consideration transferred			$ 76,600,000	$ 76,600,000
Milestone achievement period			5 years	12 months
Goodwill			$ 17,612,000
Acquisition related costs				$ 0	3,300,000	$ 800,000
Net sales from acquisition				12,400,000	8,700,000
Net loss from Acquisition				9,300,000	$ 5,800,000
Spinal Kinetics [Member] | Developed Technology [Member]
Business Acquisition [Line Items]
Business acquisition, transfer from indefinite lived intangible assets to finite lived intangible assets	$ 26,800,000
Assigned Useful Life	10 years		10 years
Spinal Kinetics [Member] | Spinal Implants [Member]
Business Acquisition [Line Items]
Goodwill				$ 17,600,000
Spinal Kinetics [Member] | US Food And Drug Administration [Member]
Business Acquisition [Line Items]
Future milestone payments	$ 15,000,000.0		$ 15,000,000.0
Spinal Kinetics [Member] | Revenue Milestone [Member]
Business Acquisition [Line Items]
Future milestone payments			45,000,000.0
Spinal Kinetics [Member] | Maximum [Member]
Business Acquisition [Line Items]
Future milestone payments			$ 60,000,000.0